How can i strip the HTML from document between and including the <...> tags in a HTML document using C? My current program uses curl to get the contents of the webpage and puts it into a text file, it then reads from the text file and removes the <>, but i am unsure of how to remove everything between those tags.
#include <curl/curl.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#define WEBPAGE_URL "http://homepages.paradise.net.nz/adrianfu/index.html"
#define DESTINATION_FILE "/home/user/data.txt"
size_t write_data( void *ptr, size_t size, size_t nmeb, void *stream)
{
return fwrite(ptr,size,nmeb,stream);
}
int main()
{
int in_tag = 0;
char * buffer;
char c;
long lSize;
size_t result;
FILE * file = fopen(DESTINATION_FILE,"w+");
if (file==NULL) {
fputs ("File error",stderr);
exit (1);
}
CURL *handle = curl_easy_init();
curl_easy_setopt(handle,CURLOPT_URL,WEBPAGE_URL); /*Using the http protocol*/
curl_easy_setopt(handle,CURLOPT_WRITEFUNCTION, write_data);
curl_easy_setopt(handle,CURLOPT_WRITEDATA, file);
curl_easy_perform(handle);
curl_easy_cleanup(handle);
int i, nRead, fd;
int source;
char buf[1024];
if((fd = open("data.txt", O_RDONLY)) == -1)
{
printf("Cannot open the file");
}
else
{
nRead = read(fd, buf, 1024);
printf("Original String ");
for(i=0; i<nRead; i++)
{
printf("%c", buf[i]);
}
printf("\nReplaced String ");
for(i=0; i<nRead; i++)
{
if(buf[i]=='<' || buf[i]=='>'){
buf[i]=' ';
}
printf("%c", buf[i]);
}
}
close(source);
return 0;
}
Placing just the code that removes the contents between the '<' and '>' tags (assuming that you deal with proper html, meaning that you don't have one tag nested in the declaration of the other like <html < body> >). I am just changing a small portion of your code. I will also remove the tags from the buf variable, instead of replacing the undesired characters with intervals, because I think this will be more useful to you (correct me if I am wrong).
int idx = 0;
int opened = 0; // false
for(i=0; i<nRead; i++)
{
if(buf[i]=='<') {
opened = 1; // true
} else if (buf[i] == '>') {
opened = 0; // false
} else if (!opened) {
buf[idx++] = buf[i];
}
}
buf[idx] = '\0';
printf("%s\n", buf);
This would also handle scripts and style tags
int stripHTMLTags(char *sToClean,size_t size)
{
int i=0,j=0,k=0;
int flag = 0; // 0: searching for < or & (& as in &bspn; etc), 1: searching for >, 2: searching for ; after &, 3: searching for </script>,</style>, -->
char tempbuf[1024*1024] = "";
char searchbuf[1024] = "";
while(i<size)
{
if(flag == 0)
{
if(sToClean[i] == '<')
{
flag = 1;
tempbuf[0] = '\0';
k=0; // track for <script>,<style>, <!-- --> etc
}
else if(sToClean[i] == '&')
{
flag = 2;
}
else
{
sToClean[j] = sToClean[i];
j++;
}
}
else if(flag == 1)
{
tempbuf[k] = sToClean[i];
k++;
tempbuf[k] = '\0';
//printf("DEBUG: %s\n",tempbuf);
if((0 == strcmp(tempbuf,"script")))
{
flag = 3;
strcpy(searchbuf,"</script>");
//printf("DEBUG: Detected %s\n",tempbuf);
tempbuf[0] = '\0';
k = 0;
}
else if((0 == strcmp(tempbuf,"style")))
{
flag = 3;
strcpy(searchbuf,"</style>");
//printf("DEBUG: Detected %s\n",tempbuf);
tempbuf[0] = '\0';
k = 0;
}
else if((0 == strcmp(tempbuf,"!--")))
{
flag = 3;
strcpy(searchbuf,"-->");
//printf("DEBUG: Detected %s\n",tempbuf);
tempbuf[0] = '\0';
k = 0;
}
if(sToClean[i] == '>')
{
sToClean[j] = ' ';
j++;
flag = 0;
}
}
else if(flag == 2)
{
if(sToClean[i] == ';')
{
sToClean[j] = ' ';
j++;
flag = 0;
}
}
else if(flag == 3)
{
tempbuf[k] = sToClean[i];
k++;
tempbuf[k] = '\0';
//printf("DEBUG: %s\n",tempbuf);
//printf("DEBUG: Searching for %s\n",searchbuf);
if(0 == strcmp(&tempbuf[0] + k - strlen(searchbuf),searchbuf))
{
flag = 0;
//printf("DEBUG: Detected END OF %s\n",searchbuf);
searchbuf[0] = '\0';
tempbuf[0] = '\0';
k = 0;
}
}
i++;
}
sToClean[j] = '\0';
return j;
}
Related
Why am I getting this message in hackerrank "~ no response on stdout ~"? I don't know what I am missing?
I am bit frustrated right now because I have no clue about what to do.
So I was left with only choice to post this query on Stackoverflow.
Here is the link to the problem
Here is my complete code:
char* readline();
// Complete the countingValleys function below.
int countingValleys(int n, char* s)
{
int dwnhl = 0, level = 0;
bool frmsurface = true;
int k = strlen(s);
for (int i = 0; i < k; i++)
{
if (level == 0)
{
frmsurface = true;
}
if (s[i] == 'D')
{
level--;
if ((level < 0) && (frmsurface == true))
{
dwnhl++;
frmsurface = false;
//printf("went downhill %d ",i);
}
}
else if (s[i] == 'U')
{ //printf("went uphill %d ",i);
level++;
}
// printf("\nhello - %c",s[i]);
}
printf("\nNumber of downhill = %d \n", dwnhl);
return (dwnhl);
}
int main()
{
FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");
char* n_endptr;
char* n_str = readline();
int n = strtol(n_str, &n_endptr, 10);
if (n_endptr == n_str || *n_endptr != '\0')
{
exit(EXIT_FAILURE);
}
char* s = readline();
int result = countingValleys(n, s);
printf("%d\n", result);
return 0;
}
char* readline()
{
size_t alloc_length = 1024;
size_t data_length = 0;
char* data = malloc(alloc_length);
while (true)
{
char* cursor = data + data_length;
char* line = fgets(cursor, alloc_length - data_length, stdin);
if (!line)
{
break;
}
data_length += strlen(cursor);
if (data_length < alloc_length - 1 || data[data_length - 1] == '\n')
{
break;
}
size_t new_length = alloc_length << 1;
data = realloc(data, new_length);
if (!data)
{
break;
}
alloc_length = new_length;
}
if (data[data_length - 1] == '\n')
{
data[data_length - 1] = '\0';
}
data = realloc(data, data_length);
return data;
}
One problem is the way you handle frmsurface
The first time you enter the loop frmsurface is set to true. If the events are UUDD, your code will still count a "valley" because you don't clear frmsurface when you go up.
Instead of
if(level==0)
{
frmsurface=true;
}
you could try:
frmsurface = (level == 0);
but I don't really understand why you want the boolean. Just test for level == 0 instead. Something like:
if(s[i]=='D')
{
if(level==0)
{
dwnhl++;
}
level--;
}
else if (s[i]=='U')
{
level++;
}
Also I wonder if this line:
printf("\nNumber of downhill = %d \n", dwnhl);
must be removed.
Notice that
int k=strlen(s);
for(int i=0;i<k;i++)
could probably just be
for(int i=0;i<n;i++)
^
as n is passed to the function
Hi I've recently started learning unix system programming.
I'm trying to create a minishell in c but when I run my code,
I always get:
EXC_BAD_ACCESS (code=EXC_I386_GPFLT
Don't really know what's wrong here. Searched online they say it's something wrong with malloc, but I don't see what's wrong.
Can someone help me with this problem?
#include <stdlib.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string.h>
#include <unistd.h>
#include "minishell.h"
char promptString[] = "mysh>";
struct command_t command;
int enviromentlength;
int commandlength;
char *pathv[MAX_PATHS];
//to display the prompt in the front of every line
void printPrompt()
{
printf("%s", promptString);
}
//get the user's command
void readCommand(char *buffer)
{
gets(buffer);
}
//get the environment variable and store in a pathEnvVar
int parsePath( char* dirs[] )
{
char* pathEnvVar;
char* thePath;
int i;
for(i = 0; i < MAX_ARGS; i++)
{
dirs[i] = NULL;
}
i = 0;
//use system call to get the environment variable
pathEnvVar = (char*) getenv("PATH");
//printf("%s\n", pathEnvVar);
thePath = (char*) malloc(strlen(pathEnvVar) + 1);
strcpy(thePath, pathEnvVar);
//splict the variable and store in the pathv
char *temp = strtok(thePath, ":");
dirs[i] = temp;
while(temp != NULL)
{
i++;
temp = strtok(NULL, ":");
if(temp == NULL)
{
break;
}
else
{
dirs[i] = temp;
}
}
dirs[i+1] = NULL;
return i;
}
//get the user's command and parameters
int parseCommand(char * commandline)
{
int i = 0;
char* temp;
temp = strtok(commandline, " ");
while(temp != NULL)
{
command.argv[i] = temp;
i++;
temp = strtok(NULL, " ");
}
command.argv[i] = NULL;
return i;
}
//input the user's command to
//fix the absolute path of the command
char* lookupPath(char* dir[], char* command[])
{
char* result = NULL;
int i;
//printf("%c\n", *command.argv[0]);
//if the command is already an absolute path
if(*command[0] == '/')
{
result = command[0];
//printf("test\n");
if( access(result, X_OK) == 0)
{
return result;
}
else
{
fprintf(stderr, "%s: command not found\n", result);
return NULL;
}
}
//if the command is not an absolute path
else
{
for(i = 0; i < enviromentlength; i++)
{
char *temp = (char *) malloc (30);
strcpy(temp, dir[i]);
strcat(temp, "/");
strcat(temp, command[0]);
result = temp;
if( access(result, X_OK) == 0)
{
return result;
}
}
fprintf(stderr, "%s: command not found\n", result);
return NULL;
}
}
//to change the directory and
//display the absolute path of the current directory
void do_cd(char* dir[])
{
char currentdirectory[MAX_PATHS];
if(dir[1] == NULL || (strcmp(dir[1], ".") == 0))
{
printf("director does not change\n");
//printf("The current directory is:%s", currentdirectory);
}
else
{
if(chdir(dir[1]) < 0)
{
printf("change director error\n");
}
else
{
printf("change director success\n");
}
}
getcwd(currentdirectory, MAX_PATHS);
printf("The current directory is:%s\n", currentdirectory);
}
//redirection the result to file
void redirection(char* command, char* commandcontent[], int position, pid_t thisChPID)
{
char* content[commandlength - 1];
char* filename = (char *) malloc(MAX_PATH_LEN);
FILE* fid;
int i = 0;
int stat;
strcpy(filename, commandcontent[position + 1]);
//printf("%s\n", commandcontent[position + 1]);
for(i = 0; i < position; i++)
{
content[i] = commandcontent[i];
//printf("content: %s\n", content[i]);
}
content[i + 1] = NULL;
for(i = 0; i< position + 1; i++)
{
printf("%s\n", content[i]);
}
printf("%s\n", command);
if((thisChPID=fork()) < 0)
{
fprintf(stderr, "fork failed\n");
}
else if(thisChPID == 0)
{
fid = open(filename, O_WRONLY || O_CREAT);
close(1);
dup(fid);
close(fid);
execve(command, content, pathv);
}
else
{
wait(&stat);
}
}
//use pipe to run the program
void piperun(char* command, char* commandcontent[], int position, pid_t thisChPID)
{
printf("%s\n%d\n", command, position);
char* firstcommand[position+1];
char* secondcommand[commandlength-position];
char* result = (char *) malloc(MAX_PATH_LEN);
pid_t child;
//the pipe name
int pipeID[2];
int j;
for(j = 0; j< position; j++)
{
firstcommand[j] = commandcontent[j];
printf("%s\n", firstcommand[j]);
}
firstcommand[j] = NULL;
printf("length: %d\n", commandlength-position);
for(j = 0; j < (commandlength-position); j++)
{
secondcommand[j] = commandcontent[position + 1 + j];
printf("second:%s\n",secondcommand[j]);
}
//secondcommand[j+1] = NULL;
result = lookupPath(pathv, secondcommand);
//printf("%s\n", secondcommand[0]);
printf("%s\n", result);
//create pipe "pipeID"
if(pipe(pipeID)==-1)
{
printf("Fail to creat pipe.\n");
}
if((thisChPID=fork())==-1)
{
printf("Fail to creat child process.\n");
}
if(thisChPID==0)
{
printf("in the child\n");
close(1);
dup(pipeID[1]);
close(pipeID[0]);
close(pipeID[1]);
if(execve(command, firstcommand, pathv)==-1)
{
printf("Child process can't exec command %s.\n",firstcommand[0]);
}
}
else
{
child = fork();
if((child=fork())==-1)
{
printf("Fail to creat child process.\n");
}
if(child==0)
{
close(0);
dup(pipeID[0]);
close(pipeID[1]);
close(pipeID[0]);
if(execve(result, secondcommand, pathv)==-1)
{
printf("Child process can't exec command %s.\n",secondcommand[0]);
}
}
else
{
wait(NULL);
}
}
}
int main()
{
char commandLine[LINE_LEN];
int child_pid; //child process id
int stat; //used by parent wait
pid_t thisChPID;
char *arg[MAX_ARGS];
//the flag of redirection, piping and background running
int redirectionsituation = 0;
int pipesituation = 0;
int background = 0;
char * tempchar;
//Command initialization
int i;
for(i = 0; i < MAX_ARGS; i++ )
{
command.argv[i] = (char *) malloc(MAX_ARG_LEN);
}
//get all directories from PATH env var
enviromentlength = parsePath(pathv);
//Main loop
while(TRUE)
{
redirectionsituation = 0;
pipesituation = 0;
background = 0;
//Read the command line
printPrompt();
readCommand(commandLine);
//input nothing
if(commandLine[0] == '\0')
{
continue;
}
//quit the shell?
if((strcmp(commandLine, "exit") == 0) || (strcmp(commandLine, "quit") == 0))
{
break;
}
//if it is background running
if(commandLine[strlen(commandLine) - 1] == '&')
{
printf("backgrond\n");
tempchar = strtok (commandLine, "&");
//strcpy(commandLine, tempchar);
printf("%s\n", tempchar);
background = 1;
}
//Parse the command line
commandlength = parseCommand(commandLine);
//if the command is "cd"
if(strcmp(command.argv[0], "cd") == 0)
{
do_cd(command.argv);
continue;
}
//Get the full path name
command.name = lookupPath(pathv, command.argv);
printf("command name %s\n", command.name);
//report error
if( command.name == NULL)
{
continue; //non-fatal
}
//if redirection is required
for(i = 0; i < commandlength; i++)
{
if(strcmp(command.argv[i], ">") == 0)
{
redirectionsituation = 1;
break;
}
}
if(redirectionsituation == 1)
{
redirection(command.name, command.argv, i, thisChPID);
continue;
}
//if pipe is required
for(i = 0; i < commandlength; i++)
{
if(strcmp(command.argv[i], "|") == 0)
{
pipesituation = 1;
break;
}
}
if(pipesituation == 1)
{ //run pipe
piperun(command.name, command.argv, i, thisChPID);
continue;
}
//normal running
if((thisChPID=fork()) < 0)
{
fprintf(stderr, "fork failed\n");
}
else if(thisChPID == 0)
{
//printf("run again\n");
execve(command.name, command.argv, pathv);
}
else
{
//do not put the process in the background, wait until the child process terminates
if(background == 0)
{
wait(&stat);
}
}
}
return 0;
}
Run it in a debugger and see where you are dereferencing a null.
My code is not working and it is when I call fgets in the commandSplit function. I figured this out by printing "Am I here" in multiple places and find that the error at fgets it seems. I may be wrong, but I am pretty sure. I get a segmentation fault and I can not figure out why. Below is my code.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#define MAX_CHARACTERS 512
int Execute(char *a[], int t[], int num) {
int exitShell = 0;
int l = 0;
for (int i = 0; i < num; i++) {
int status;
if (strcmp(a[0], "quit") == 0) {
exitShell = 1;
}
if (t[i] && ((strcmp(a[l], "quit") == 0))) {
exitShell = 1;
}
char *holder[t[i]+1];
for (int j = 0; j < t[i]; j++) {
holder[j] = a[l];
l++;
}
holder[t[i]] = NULL;
pid_t p = fork();
pid_t waiting;
if (p == 0) {
execvp(holder[0], holder);
fprintf(stderr, "Child process could not execvp!\n");
exit(1);
} else {
if (p < 0) {
fprintf(stderr, "Fork FAILED!\n");
} else {
waiting = wait(&status);
printf("Child %d exit with status %d\n", waiting, status);
}
}
for (int g = 0; g < t[i]; g++) {
a[g] = NULL;
}
}
for (int i = 0; i < num; i++) {
t[i] = 0;
}
return exitShell;
}
int commandSplit(char *c, FILE *f, char *a[], int t[]) {
int count = 0;
int emptyfile = 1;
int stat = 0;
int total1 = 0;
char *temp[MAX_CHARACTERS];
if (c != NULL) {
char *readCommands = strtok(c, ";");
while (readCommands != NULL) {
temp[count] = readCommands;
count++;
readCommands = strtok(NULL, ";");
}
for (int i = 0; i < count; i++) {
char *read = strtok(temp[i], " ");
int track1 = 0;
while (read != NULL) {
a[total1] = read;
track1++;
total1++;
read = strtok(NULL, " ");
}
t[i] = track1;
}
stat = Execute(a, t, count);
} else {
char *buildCommands = "";
printf("Am I here???\n");
while ((fgets(buildCommands, MAX_CHARACTERS, f) != NULL) && !stat) {
printf("Am I here???\n");
emptyfile = 0;
commandSplit(buildCommands, NULL, a, t);
stat = Execute(a, t, count);
}
if (emptyfile) {
printf("File is empty!\n");
stat = 1;
}
}
printf("Am I here???\n");
return stat;
}
int main(int argc, char *argv[]) {
int exitProgram = 0;
FILE *fileRead = NULL;
if (argc == 2) {
fileRead = fopen(argv[1], "r");
if (fileRead == NULL) {
printf("No such file exists\n");
exitProgram = 1;
}
}
if (argc > 2) {
printf("Incorrect batch mode call\n");
exitProgram = 1;
}
char *args[MAX_CHARACTERS];
int tracker[MAX_CHARACTERS];
while (!exitProgram) {
if (argc == 1) {
char *commands = (char *)(malloc(MAX_CHARACTERS * sizeof(char)));
printf("tinyshell>");
if (fgets(commands, MAX_CHARACTERS, stdin) == NULL) {
exitProgram = 1;
printf("\n");
}
int len;
len = strlen(commands);
if (len > 0 && commands[len-1] == '\n') {
commands[len-1] = '\0';
}
if (len > MAX_CHARACTERS) {
printf("TOO MANY CHARACTERS - MAX: 512\n");
continue;
}
if (strlen(commands) == 0)
continue;
exitProgram = commandSplit(commands, NULL, args, tracker);
} else {
exitProgram = commandSplit(NULL, fileRead, args, tracker);
}
}
fclose(fileRead);
return 0;
}
As commented #Jean-François Fabre , buildCommands points to insufficient space and potential const space;
char *buildCommands = "";
...
// bad code
while ((fgets(buildCommands, MAX_CHARACTERS, f) != NULL) && !stat) {
Allocate space with an array or malloc()
char buildCommands[MAX_CHARACTERS];
...
while ((fgets(buildCommands, sizeof buildCommands, f) != NULL) && !stat) {
...
}
// or
char *buildCommands = malloc(MAX_CHARACTERS);
assert(buildCommands);
...
while ((fgets(buildCommands, MAX_CHARACTERS, f) != NULL) && !stat) {
...
}
...
free(buildCommands);
my program works fine if i give hard code value to char *w="ls -l" but i am trying to take input form user not working help my code:: using input error occur
i don't understand the concept of fgets using fgets its gives the garbig value to execv
#include<stdio.h>
#include<sys/wait.h>
#include<stdbool.h>
void func(char **arr, char *w)
{
int i = 0, j = 0, k = 0;
char temp[100];
for (i = 0; i < 100; i++)
{
if (w[i] == '')
{
arr[k] = temp;
arr[k+1] = NULL;
break;
}
if (w[i] == ' ')
{
arr[k] = temp;
k++;
j = 0;
}
else
{
temp[j] = w[i];
j++;
}
}
}
int main()
{
char *n = "/bin/ls";
char *arr[10] = {''};
char p[100] = {''};
char *w = "ls -l";
int i = 0;
//printf("bilal-hassan-qadri $ >>");
//fgets(p, 100, stdin);
arr[2] = NULL;
bool found = false;
for (i = 0; i < sizeof(w); i++)
{
if (w[i] == ' ')
{
found=true;
func(arr,w);
break;
}
}
if (!found)
arr[0] = w;
int status;
int id = fork();
if (id == 0)
{
if (execv(n,arr) < 0)
{
printf("invalid commandn");
}
else
{
printf("ninvalid command");
}
}
else
{
wait(&status);
}
}
In the function func, You have to copy the string to elements of arr
instead of just passing the address of temp, which will vanish on leaving the function.
You can use strdup instead of copy_string if your system supports it.
You have to terminate the string in temp before copying it.
Empty string constant '' seems invalid. You shouldn't use it.
fgets stores new-line character \n if it exists. Check for it and remove if it isn't wanted.
Fixed code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/wait.h>
#include<stdbool.h>
char *copy_string(const char *str) {
char *s = malloc(strlen(str) + 1);
if (s) strcpy(s, str); else {perror("malloc"); exit(1);}
return s;
}
void func(char **arr, char *w)
{
int i = 0, j = 0, k = 0;
char temp[100];
for (i = 0; i < 100; i++)
{
if (w[i] == '\0' || w[i] == '\n')
{
temp[j] = '\0';
arr[k] = copy_string(temp);
arr[k+1] = NULL;
break;
}
if (w[i] == ' ')
{
temp[j] = '\0';
arr[k] = copy_string(temp);
k++;
j = 0;
}
else
{
temp[j] = w[i];
j++;
}
}
}
int main(void)
{
char *n = "/bin/ls";
char *arr[10] = {NULL};
char p[100] = {0};
char *w = "ls -l";
int i = 0;
//printf("bilal-hassan-qadri $ >>");
fgets(p, 100, stdin);
w = p;
arr[2] = NULL;
bool found = false;
for (i = 0; w[i] != '\0'; i++)
{
if (w[i] == ' ')
{
found=true;
func(arr,w);
break;
}
}
if (!found)
arr[0] = w;
int status;
int id = fork();
if (id == 0)
{
if (execv(n,arr) < 0)
{
printf("invalid commandn");
}
else
{
printf("ninvalid command");
}
}
else
{
wait(&status);
for (i = 0; arr[i] != NULL; i++) free(arr[i]);
}
return 0;
}
So, essentially I have two files:
File 1:
//
// main.c
// frederickterry
//
// Created by Rick Terry on 1/15/15.
// Copyright (c) 2015 Rick Terry. All rights reserved.
//
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int size (char *g) {
int ofs = 0;
while (*(g+ofs) != '\0') {
++ofs;
}
return ofs;
}
int parse(char *g) {
// Setup
char binaryConnective;
int negated = 0;
// Looking for propositions
int fmlaLength = size(g);
if(fmlaLength == 0) {
return 1;
}
if(fmlaLength == 1) {
if(g[0] == 'p') {
return 1;
} else if (g[0] == 'q') {
return 1;
} else if (g[0] == 'r') {
return 1;
} else {
return 0;
}
}
// Now looking for negated preposition
if(fmlaLength == 2) {
char temp[100];
strcpy(temp, g);
if(g[0] == '-') {
negated = 1;
int negatedprop = parse(g+1);
if(negatedprop == 1) {
return 2;
}
}
}
// Checking if Binary Formula
char arrayleft[50];
char arrayright[50];
char *left = "";
char *right = "";
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int binarypresent = 0;
if(fmlaLength != 1 && fmlaLength != 2) {
if(g[0] == '-') {
int negatedBinary = parse(g+1);
if(negatedBinary == 1 || negatedBinary == 2 || negatedBinary == 3) {
return 2;
} else {
return 0;
}
}
int i = 0;
int l = 0;
int p = strlen(g);
for(l = 0; l < strlen(g)/2; l++) {
if(g[l] == '(' && g[p-l-1] == ')') {
i++;
}
}
for(int q = i; q < strlen(g); q++) {
if(g[q] == '(') {
numLeft++;
} else if(g[q] == ')') {
numRight++;
}
arrayleft[q] = g[q];
//printf("%c", arrayleft[i]);
//printf("%s", left);
if((numRight == numLeft) && (g[q+1] == 'v' || g[q+1] == '>' || g[q+1] == '^')) {
arrayleft[q+1] = '\0';
bclocation = q+1;
binaryConnective = g[q+1];
binarypresent = 1;
// printf("The binary connecive is: %c\n", binaryConnective);
break;
}
}
if(binarypresent == 0) {
return 0;
}
int j = 0;
for(int i = bclocation+1; i < strlen(g)-1; i++) {
arrayright[j] = g[i];
j++;
}
arrayright[j] = '\0';
left = &arrayleft[1];
right = &arrayright[0];
//printf("Printed a second time, fmla 1 is: %s", left);
int parseleft = parse(left);
// printf("Parse left result: %d\n", parseleft);
if(parseleft == 0) {
return 0;
}
int parseright = parse(right);
if(parseright == 0) {
return 0;
}
// printf("Parse right result: %d\n", parseleft);
if(negated == 1) {
return 2;
} else {
return 3;
}
}
return 0;
}
int type(char *g) {
if(parse(g) == 1 ||parse(g) == 2 || parse(g) == 3) {
if(parse(g) == 1) {
return 1;
}
/* Literals, Positive and Negative */
if(parse(g) == 2 && size(g) == 2) {
return 1;
}
/* Double Negations */
if(g[0] == '-' && g[1] == '-') {
return 4;
}
/* Alpha & Beta Formulas */
char binaryConnective;
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int binarypresent = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
bclocation = i+1;
binaryConnective = g[i+1];
binarypresent = 1;
break;
}
}
}
/* Connective established */
if(binaryConnective == '^') {
if(g[0] == '-') {
return 3;
} else {
return 2;
}
} else if(binaryConnective == '>') {
if(g[0] == '-') {
return 2;
} else {
return 3;
}
} else if (binaryConnective == 'v') {
if(g[0] == '-') {
return 2;
} else {
return 3;
}
}
}
return 0;
}
char bin(char *g) {
char binaryConnective;
char arrayLeft[50];
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
int j = 0;
arrayLeft[j++] = g[i];
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
arrayLeft[i+1] = '\0';
bclocation = i+1;
binaryConnective = g[i+1];
return binaryConnective;
}
}
}
return binaryConnective;
}
char *partone(char *g) {
char binaryConnective;
char arrayLeft[50];
char arrayRight[50];
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
int j = 0;
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
arrayLeft[j] = g[i];
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
arrayLeft[j+1] = '\0';
bclocation = i+1;
binaryConnective = g[i+1];
break;
}
}
j++;
}
int m = 0;
for(int k = bclocation+1; k < strlen(g)-1; k++) {
arrayRight[m] = g[k];
m++;
}
arrayRight[m] = '\0';
char* leftSide = &arrayLeft[0];
// printf("%s\n", leftSide);
// printf("%s\n", rightSide);
int k = 0;
k++;
return leftSide;
}
char *parttwo(char *g) {
char binaryConnective;
char arrayLeft[50];
char arrayRight[50];
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
int j = 0;
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
arrayLeft[j] = g[i];
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
arrayLeft[j+1] = '\0';
bclocation = i+1;
binaryConnective = g[i+1];
break;
}
}
j++;
}
int m = 0;
int n = size(g) - 1;
if(g[strlen(g)-1] != ')') {
n++;
}
for(int k = bclocation+1; k < n; k++) {
arrayRight[m] = g[k];
m++;
}
arrayRight[m] = '\0';
char* leftSide = &arrayLeft[0];
char* rightSide = &arrayRight[0];
// printf("%s\n", leftSide);
// printf("%s\n", rightSide);
return rightSide;
}
char *firstexp(char *g) {
char* left = partone(g);
char leftArray[50];
int i = 0;
for(i; i < strlen(left); i++) {
leftArray[i] = left[i];
}
leftArray[i] = '\0';
char binConnective = bin(g);
int typeG = type(g);
if(typeG == 2) {
if(binConnective == '^') {
return &leftArray;
} else if(binConnective == '>') {
return &leftArray;
}
} else if(typeG == 3) {
if(binConnective == 'v')
return &leftArray;
}
char temp[50];
for(int i = 0; i < strlen(leftArray); i++) {
temp[i+1] = leftArray[i];
}
temp[0] = '-';
char* lefttwo = &temp[0];
if(typeG == 2) {
if(binConnective == 'v') {
return lefttwo;
}
} else if(typeG == 3) {
if(binConnective == '>' || binConnective == '^') {
return lefttwo;
}
}
return "Hello";
}
char *secondexp(char *g) {
// char binaryConnective = bin(g);
// char* right = parttwo(g);
// char rightArray[50];
// int i = 0;
// for(i; i< strlen(right); i++) {
// rightArray[i+1] = right[i];
// }
// rightArray[i] = '\0';
// int typeG = type(g);
// if(type(g) == 2) {
// if(binaryConnective == '^') {
// return &rightArray;
// }
// } else if(type(g) == 3) {
// if(binaryConnective == 'v' || binaryConnective == '>') {
// return &rightArray;
// }
// }
return "Hello";
}
typedef struct tableau tableau;
\
\
struct tableau {
char *root;
tableau *left;
tableau *right;
tableau *parent;
int closedbranch;
};
int closed(tableau *t) {
return 0;
}
void complete(tableau *t) {
}
/*int main(int argc, const char * argv[])
{
printf("Hello, World!\n");
printf("%d \n", parse("p^q"));
printf("%d \n", type("p^q"));
printf("%c \n", bin("p^q"));
printf("%s\n", partone("p^q"));
printf("%s\n", parttwo("p^q"));
printf("%s\n", firstexp("p^q"));
printf("Simulation complete");
return 0;
}*/
File 2:
#include <stdio.h>
#include <string.h> /* for all the new-fangled string functions */
#include <stdlib.h> /* malloc, free, rand */
#include "yourfile.h"
int Fsize = 50;
int main()
{ /*input a string and check if its a propositional formula */
char *name = malloc(Fsize);
printf("Enter a formula:");
scanf("%s", name);
int p=parse(name);
switch(p)
{case(0): printf("not a formula");break;
case(1): printf("a proposition");break;
case(2): printf("a negated formula");break;
case(3): printf("a binary formula");break;
default: printf("what the f***!");
}
printf("\n");
if (p==3)
{
printf("the first part is %s and the second part is %s", partone(name), parttwo(name));
printf(" the binary connective is %c \n", bin(name));
}
int t =type(name);
switch(t)
{case(0):printf("I told you, not a formula");break;
case(1): printf("A literal");break;
case(2): printf("An alpha formula, ");break;
case(3): printf("A beta formula, ");break;
case(4): printf("Double negation");break;
default: printf("SOmewthing's wrong");
}
if(t==2) printf("first expansion fmla is %s, second expansion fmla is %s\n", firstexp(name), secondexp(name));
if(t==3) printf("first expansion fmla is %s, second expansion fmla is %s\n", firstexp(name), secondexp(name));
tableau tab;
tab.root = name;
tab.left=0;
tab.parent=0;
tab.right=0;
tab.closedbranch=0;
complete(&tab);/*expand the root node then recursively expand any child nodes */
if (closed(&tab)) printf("%s is not satisfiable", name);
else printf("%s is satisfiable", name);
return(0);
}
If you look at the first file, you'll see a method called * firstexp(char * g).
This method runs perfectly, but only if another method called * secondexp(char * g) is commented out.
If * secondexp(char * g) is commented out, then *firstexp runs like this:
Enter a formula:((pvq)>-p)
a binary formula
the first part is (pvq) and the second part is -p the binary connective is >
A beta formula, first expansion fmla is -(pvq), second expansion fmla is Hello
((pvq)>-p) is satisfiableProgram ended with exit code: 0
otherwise, if *secondexp is not commented out, it runs like this:
Enter a formula:((pvq)>-p)
a binary formula
the first part is (pvq) and the second part is -p the binary connective is >
A beta formula, first expansion fmla is \240L, second expansion fmla is (-
((pvq)>-p) is satisfiable. Program ended with exit code: 0
As you can see, the outputs are completely different despite the same input. Can someone explain what's going on here?
In the commented-out parts of secondexp and in parttwo, you return the address of a local variable, which you shouldn't do.
You seem to fill a lot of ad-hoc sized auxiliary arrays. These have the problem that they might overflow for larger expressions and also that you cannot return them unless you allocate them on the heap with malloc, which also means that you have to free them later.
At first glance, the strings you want to return are substrings or slices of the expression string. That means that the data for these strings is already there.
You could (safely) return pointers into that string. That is what, for example strchr and strstr do. If you are willing to modify the original string, you could also place null terminators '\0' after substrings. That's what strtok does, and it has the disadvantage that you lose the information at that place: If you string is a*b and you modify it to a\0b, you will not know which operator there was.
Another method is to create a struct that stores a slice as pointer into the string and a length:
struct slice {
const char *p;
int length;
};
You can then safely return slices of the original string without needing to worry about additional memory.
You can also use the standard functions in most cases, if you stick to the strn variants. When you print a slice, you can do so by specifying a field width in printf formats:
printf("Second part: '%.*s'\n", s->length, s->p);
In your parttwo() function you return the address of a local variable
return rightSide;
where rightSide is a pointer to a local variable.
It appears that your compiler gave you a warning about this which you solved by making a pointer to the local variabe arrayRight, that may confuse the compiler but the result will be the same, the data in arrayRight will no longer exist after the function returns.
You are doing the same all over your code, and even worse, in the secondexp() function you return a the address of a local variable taking it's address, you are not only returning the address to a local variabel, but also with a type that is not compatible with the return type of the function.
This is one of many probable issues that your code may have, but you need to start fixing that to continue with other possible problems.
Note: enable extra warnings when compiler and listen to them, don't try to fool the compiler unless you know exactly what you're doing.