I have the following to parse a csv file, and it works fine until i changed
(getfield(tmp, 12));
to
(getfield(tmp, ver));
Is the problem in function declaration ?
here is the code :
const char* getfield(char* line, int num)
{
const char* tok;
for (tok = strtok(line, ";");
tok && *tok;
tok = strtok(NULL, ";\n"))
{
if (!--num)
return tok;
}
return NULL;
}
int main() {
double frame_index[40][300];
int horz;
FILE* fp = fopen("output.txt", "r");
char line[1024];
for (int ver; ver<20;ver++) {
while (fgets(line, 1024, fp)) {
char* tmp = strdup(line);
frame_index[ver][horz] = atof(getfield(tmp, ver));
// works if "ver" was explicitly defined
printf("AA %f\n", frame_index[ver][horz]);
free(tmp);
horz++;
}
rewind(fp);
}
}
You never initialize the variable ver. For example you might want to change
for (int ver; ver<20;ver++)
to
for (int ver=0; ver<20;ver++)
Update The same with horz..
Related
How i can create a function for reading structure from a test.txt. I have a good works code in main, but i need to carry out it from main(). How combine (struct student PI1[N] and (fread() or fgets() or fwrite()));
struct student {
char surname[50];
char name[50];
char dayBirth[50];
int mark;
};
struct student PI1[N];
int main()
{
int counter = 0;
char str[50];
const char s[2] = " ";
char* token;
FILE* ptr;
int i = 0;
ptr = fopen("test.txt", "r");
if (NULL == ptr) {
printf("file can't be opened \n");
}
char* tmp;
int Itmp;
while (fgets(str, 50, ptr) != NULL) {
token = strtok(str, s);
strcpy(PI1[i].surname, token);
token = strtok(NULL, s);
strcpy(PI1[i].name, token);
token = strtok(NULL, s);
strcpy(PI1[i].dayBirth, token);
token = strtok(NULL, s);
Itmp = atoi(token);
PI1[i].mark = Itmp;
i++;
counter++;
}
}
Rather than "can create a function for reading structure from a test.txt", start with a function to convert a string from fgets() into a struct. Then call it as needed.
Use sprintf() and " %n" to detect complete scan with no extra text.
// Return success flag
bool string_to_student(struct student *stu, const char *s) {
int n = 0;
sscanf(s, "%49s%49s%49s%d %n", stu->surname, stu->name,
stu->dayBirth, &stu->mark, &n);
return n > 0 && s[n] == '\0';
}
Use
while (i < N && fgets(str, sizeof str, ptr) &&
string_to_student(&PI1[i], str)) {
i++;
}
counter = i;
I have tried using a function that would work in "regular" c:
const char* getfield(char* line, int num)
{
const char* tok;
for (tok = strtok(line, ";");
tok && *tok;
tok = strtok(NULL, ";\n"))
{
if (!--num)
return tok;
}
return NULL;
}
int main()
{
FILE* stream = fopen("v1.csv", "r");
char line[1024];
while (fgets(line, 1024, stdin))
{
char* tmp = strdup(line);
printf("Field 3 would be %s\n", getfield(tmp, 3));
// NOTE strtok clobbers tmp
free(tmp);
}
}
I am trying to read a file names "v1.csv" located in my pebble app resources folder.
You can not read/write to files, use file descriptor or any of the f* functions in the Pebble SDK.
If you want to store data on the watch, you should look into the Persistent Storage API.
I'm writing a basic program that takes a CSV file, prints the first field, and does some numerical evaluation of the other fields.
I'm looking to put all the numerical fields into an array but every time I do this and try to access a random element of the array, it prints the entire thing
My CSV file is:
Exp1,10,12,13
Exp2,15,16,19
and i'm trying to access the second field so it prints
Exp1 12
Exp2 16
but instead I'm getting
Exp1 101213
Exp2 151619
If someone could provide some suggestions. This is my code:
#define DELIM ","
int main(int argc, char *argv[])
{
if(argc == 2) {
FILE *txt_file;
txt_file = fopen(argv[1], "rt");
if(!txt_file) {
printf("File does not exist.\n");
return 1;
}
char tmp[4096];
char data[4096];
char expName[100];
char *tok;
int i;
while(1){
if(!fgets(tmp, sizeof(tmp), txt_file)) break;
//prints the experiment name
tok = strtok(tmp, DELIM);
strncpy(expName, tok, sizeof(expName));
printf("\n%s ", expName);
while(tok != NULL) {
tok = strtok(NULL, DELIM);
//puts data fields into an array
for(i=0; i < sizeof(data); i++) {
if(tok != NULL) {
data[i] = atoi(tok);
}
}
printf("%d", data[1]);
}
}
fclose(txt_file);
return 0;
}
sample to fix
char tmp[4096];
int data[2048];
char expName[100];
char *tok;
int i=0;
while(fgets(tmp, sizeof(tmp), txt_file)){
tok = strtok(tmp, DELIM);
strncpy(expName, tok, sizeof(expName));
printf("\n%s ", expName);
while((tok = strtok(NULL, DELIM))!=NULL){
data[i++] = atoi(tok);
}
printf("%d", data[1]);
i = 0;
}
A modified code snippet:
int data[20]; // change 20 to a reasonable value
...
while (1)
{ if (!fgets(tmp, sizeof(tmp), txt_file))
break;
//prints the experiment name
tok = strtok(tmp, DELIM);
strncpy(expName, tok, sizeof(expName));
printf("\n%s ", expName);
i = 0;
tok = strtok(NULL, DELIM);
while (tok != NULL)
{ //puts data fields into an array
data[i++] = atoi(tok);
if (i == 20)
break;
tok = strtok(NULL, DELIM);
}
if (i > 1)
printf("%d", data[1]);
}
I tried really hard to search for a solution to this but I can't think of good enough keywords.
Currently I'm having troubles grasping the concept behind makeargv and it's usage with triple pointers (I have no idea what ***foo means, it doesn't seem to be as easy of a concept as **foo or *foo). So I made my own:
const char **makeargv(char *string, int *numargs) {
string = string + strspn(string, delims);
char *copy = malloc(strlen(string) + 1);
int i;
strcpy(copy, string);
int numtokens;
if (strtok(copy, delims) != NULL) {
for (numtokens = 1; strtok(NULL, delims) != NULL; numtokens++) {}
}
strcpy(copy, string);
const char *results[numtokens+1];
results[0] = strtok(copy, delims);
for (i = 1; i < numtokens; i++) {
results[i] = strtok(NULL, delims);
}
results[numtokens+1] = NULL;
*numargs = numtokens;
return results;
}
Here's the part at where it breaks:
void parse_file(char* filename) {
char* line = malloc(160*sizeof(char));
FILE* fp = file_open(filename);
int i = 0;
int numargs = 0;
int *pointer = &numargs;
while((line = file_getline(line, fp)) != NULL) {
if (strlen(line) == 1){
continue;
}
const char **args = makeargv(line, pointer);
printf("%s\n", args[0]);
printf("%s\n", args[1]);
/* This prints out args[0], but then args[1] causes a seg fault. Even if I replace
the args[1] with another args[0] it still causes a seg fault */
}
fclose(fp);
free(line);
}
I have a working array of strings. However when I try to print out the strings in the array, I can only print 1 of my choice and then it seg faults for any subsequent calls. lets pretend my array of strings is argv[3] = {"Yes", "no", "maybe"}, if i call argv[0], it will let me call "Yes", but any other calls (even if i call argv[0] again) do not work and cause a segfault. I can call any of the elements in the array, but once i call one the rest cease to work causing segfaults.
Help please? D: This is in C.
const char *results[numtokens+1];
This array "results" is a local variable, it is only available inside of "makeargv".
You'd better use malloc:
results = malloc(numtokens+1)
And I believe there is memory leak in your code.
You will not be able to free the memory for "char *copy"
char *copy = malloc(strlen(string) + 1);
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char **makeargv(char *string, int *numargs) {
static const char *delims = " \t\n";
string = string + strspn(string, delims);
char *copy = malloc(strlen(string) + 1), *p = copy;
strcpy(copy, string);
int numtokens;
for (numtokens = 0; strtok(p, delims); ++numtokens, p = NULL);
char **results = malloc(sizeof(char*)*(numtokens+1));
strcpy(copy, string);
int i;
p = copy;
for (i = 0; i < numtokens; ++i, p = NULL)
results[i] = strtok(p, delims);
results[i] = NULL;
*numargs = numtokens;
return results;
}
FILE *file_open(char *filename){
FILE *fp = fopen(filename, "r");
if(!fp){
perror("file_open");
exit(1);
}
return fp;
}
void parse_file(char* filename) {
char* line = malloc(160*sizeof(char));
FILE* fp = file_open(filename);
int i = 0, numargs = 0;
while(fgets(line, 160, fp)){
if (*line == '\n')
continue;
char **args = makeargv(line, &numargs);
for(i = 0;i<numargs;++i)
printf("%s\n", args[i]);
printf("\n");
if(args[0])
free(args[0]);
free(args);
}
fclose(fp);
free(line);
}
int main(int argc, char *argv[]){
parse_file(argv[1]);
return 0;
}
I want to split a html page into pieces by a tag delimiter: like <img or <div>.
I tried the following code but it doesn't work:
char source[MAXBUFLEN + 1];
FILE *fp = fopen("source.html", "r");
if (fp != NULL)
{
size_t newLen = fread(source, sizeof(char), MAXBUFLEN, fp);
if (newLen == 0) {
fputs("Error reading file", stderr);
} else {
source[++newLen] = '\0'; /* Just to be safe. */
}
}
fclose(fp);
//not working
char* strArray[10];
int i = 0;
char *token = strtok(source, "<img");
while(token != NULL)
{
strcpy(strArray[i++], token);
token = strtok(NULL, "<img");
}
printf("%s\n", strArray[3]);
What am I doing wrong? Is there any other method I can use except strtok?
As Daren has already posted, strtok() doesn't do what you want. You can use
char *ptr = strstr( source, "<img" );
instead to find the first tag, and then
ptr = strstr(ptr+4, "<img" ); // search starts direcly behind the previous "<img"
// maybe you can find a better offset
for the next occurances.
Besides, your line
strcpy(strArray[i++], token);
would crash because you have no memory allocated to the pointer.
char *strtokByWord_r(char *str, const char *word, char **store){
char *p, *ret;
if(str != NULL){
*store = str;
}
if(*store == NULL) return NULL;
p = strstr(ret=*store, word);
if(p){
*p='\0';
*store = p + strlen(word);
} else {
*store = NULL;
}
return ret;
}
char *strtokByWord(char *str, const char *word){
static char *store = NULL;
return strtokByWord_r(str, word, &store);
}
replace
char *token = strtok(source, "<img");
...
token = strtok(NULL, "<img");
to
char *token = strtokByWord(source, "<img");
...
token = strtokByWord(NULL, "<img");
The second argument to strtok is a list of delimiter characters. Each of these will be used to split the string into tokens. I don't think it does what you think it does...
If you want to go and parse an html file into tokens, you could look into lex...
What is your desired output? Do you have a test case for your input?
Your code should produce the following:
input:
<html><img src="test.png"/></html>
output:
""
"ht"
"l>"
" src=\"test.pn"
"\"/>"
"/ht"
"l>"
I somehow don't think that is what you want...