What I wont to do is to create a terminal menu that takes various types of arguments and place it in a array param. Under is the code: Here is some trouble that I have and cant find a good solution for.
if i just type 'list' I will get Not a valid command, I have to type “list “ (list and space).
Menu choice new should be like this: new “My name is hello”. param[0] = new and param[1] = My name is hello , (sow I can create a message with spaces).
How can I accomplish this?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
int menu()
{
printf(">");
char line[LINE_MAX];
int i = 0;
char *param[4];
while(fgets(line, LINE_MAX, stdin) != NULL) {
param[i++] = strtok(line, " \n");
if(param[0] != NULL) {
char *argument;
while((argument = strtok(NULL, "\n")) != NULL) {
param[i++] = argument;
}
}
if(strcmp(param[0], "new") == 0) {
//new(param[1]);
menu();
} else if(strcmp(param[0], "list") == 0) {
//list();
menu();
} else {
printf("Not a valid command.\n\n");
menu();
}
}
return 0;
}
You're delimiting on " ".
fgets reads the ENTER.
So, when you type "listENTER" and tokenise at spaces you get one token, namely "listENTER". Later you compare with "list" and, of course, it doesn't match.
Try
strtok(line, " \n"); /* maybe include tabs too? */
PS. Why are you calling menu recursively? You already have a while in the function ...
Your problem is param[i++] = strtok(line, " "); will only split on space, not on \n (newline). Try adding this to your array of delimeters.
Oh, and congratulations for some decent looking code that's clean and well formatted. A pleasant change.
I'm not sure if this causes your problem but these lines
/*new(param[1]);
/*list();
Start a comment that is never terminated.
If you want one line comments you can use:
// comment
(atleast in C++ and from C99 on)
But comments starting with /*must be ended with a */and not nested:
/* comment */
/* also multi line
allowed */
Since you start a comment in a comment your compiler should have emmited a warning, actually this shouldn't compile at all.
The reason you need to type "list " is that your first strtok tokenizes until a space character, so you need to enter one in this case. Try allowing both '\n' and space as separators, i.e. replace the second parameter of strtok with " \n".
As for quotes, you need to re-combine parameters starting from the one beginning with a quote to the one ending with one by replacing the characters in between them with spaces. Or do away with strtok and parse by manually iterating through the characters in line.
Related
I have a file and I need to check if its lines are in the following format:
name: name1,name2,name3,name4 ...
(some string, followed by ":", then a single space and after that strings separated by ",").
I tried doing it with the following code:
int result =0;
do
{
result =sscanf(rest,"%[^:]: %s%s", p1,p2,p3);
if(result==3)
{
printf("invalid!");
fclose(fpointer);
return -1;
}
}while (fgets(rest ,LINE , fpointer) != NULL);
this works good for lines like: name: name1, name2 (with space between name1, and name2).
but it fails with the following line:
name : name1,name2
I want to somehow tell sscanf not to avoid this white space before the ":".
could someone see how ?
Thanks for helping!
This works for me:
result = sscanf(rest,"%[^*:]: %[^,],%s", p1, p2, p3);
Notice the * is used to consume the space (if any).
Edit 2: I realized that I did not have a "Not found" result for any query not in the database. Changes have been made to introduce this feature. Here is the current test and test output:
Input:
3
sam
99912222
tom
11122222
harry
12299933
sam
edward
harry
Output:
Not found
=0
Not found
=0
Not found
=0
Not found
=0
sam
=99912222
Not found
=0
Not found
=0
Not found
[Infinite loop continues]
Edit: I have changed a few things in the while loop in display(). I am now getting an infinite loop printing "=0" except for the third or fourth cycle through the search. Hmmm...
By the way, thanks for the reminder of testing strings with ==. Seems like a no-brainer now.
I have done some searching and have yet to be able to understand where I have gone wrong with my code. I am working on a challenge which will result in a simple phone-book program. It will take input of a number (the number of entries to be added) then the names and associated phone numbers (no dashes or periods). After the entries have been added then the user can search for entries by name and have the number displayed in the format "name=number".
The code throws a segmentation fault with the while loop in the display() function. I assume that I am attempting to print something assigned as NULL, but I cannot figure out where I have gone wrong. Any help would be very appreciated.
Lastly, the challenge calls for me to read queries until EOF; however, this confuses me since I am to accept user input from stdin. What does EOF look like with stdin, just a register return (\n)?
(PS: This is my first attempt at linked lists, so any pointers would be greatly appreciated.)
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
void add_entry(void);
void display(void);
struct phonebook {
char name[50];
int number;
struct phonebook *next;
};
struct phonebook *firstp, *currentp, *newp;
char tempname[50];
int main() {
int N;
firstp = NULL;
scanf("%d", &N);
for (int i = 0; i < N; i++) {
add_entry();
}
display();
return 0;
}
void add_entry(void) {
newp = (struct phonebook*)malloc(sizeof(struct phonebook));
if (firstp == NULL) firstp = currentp = newp;
else {
currentp = firstp;
while (currentp->next != NULL)
currentp = currentp->next;
currentp->next = newp;
currentp = newp;
}
fgets(currentp->name, 50, stdin);
scanf("%d", ¤tp->number);
currentp->next = NULL;
}
void display(void) {
while (strcmp(tempname, "\n") != 0) {
currentp = firstp;
fgets(tempname, 50, stdin);
while (strcmp(currentp->name, tempname) != 0) {
if (currentp->next == NULL) {
printf("Not found\n");
break;
}
currentp = currentp->next;
}
printf("%s=%d\n", currentp->name, currentp->number);
}
}
Your problem is that you never find the entry you're looking for. The expression currentp->name != tempname will always be true, since those are always unequal. In C, this equality test will not compile into a character-by-character comparison, but into a comparison of pointers to currentp->name and tempname. Since those are never at the same addresses, they will never be equal.
Try !strcmp(currentp->name, tempname) instead.
The reason you crash, then, is because you reach the end of the list, so that currentp will be NULL after your loop, and then you try to print NULL->name and NULL->number, actually causing the crash.
Also, on another note, you may want to start using local variables instead of using global variables for everything.
Not sure if this solves the problem, but you can't directly compare strings with != in C. You need to use if( strcmp( string1, string2 ) == 0 ) to check.
fgets doesn't take EOF (= -1) like getchar does, but it does include '\n' and pad the rest with NULL (= 0) so checking for EOF is not really helpful, but yes you can stop after \n or NULL.
Ok, so my code currently splits a single string like this: "hello world" into:
hello
world
But when I have multiple spaces in between, before or after within the string, my code doesn't behave. It takes that space and counts it as a word/number to be analyzed. For example, if I put in two spaces in between hello and world my code would produce:
hello
(a space character)
world
The space is actually counted as a word/token.
int counter = 0;
int index = strcur->current_index;
char *string = strcur->myString;
char token_buffer = string[index];
while(strcur->current_index <= strcur->end_index)
{
counter = 0;
token_buffer = string[counter+index];
while(!is_delimiter(token_buffer) && (index+counter)<=strcur->end_index)//delimiters are: '\0','\n','\r',' '
{
counter++;
token_buffer = string[index+counter];
}
char *output_token = malloc(counter+1);
strncpy(output_token,string+index,counter);
printf("%s \n", output_token);
TKProcessing(output_token);
//update information
counter++;
strcur->current_index += counter;
index += counter;
}
I can see the problem area in my loop, but I'm a bit stumped as to how to fix this. Any help would be must appreciated.
From a coding stand point, if you wanted to know how to do this without a library as an exercise, what's happening is your loop breaks after you run into the first delimeter. Then when you loop to the second delimeter, you don't enter the second while loop and print a new line again. You can put
//update information
while(is_delimiter(token_buffer) && (index+counter)<=strcur->end_index)
{
counter++;
token_buffer = string[index+counter];
}
Use the standard C library function strtok().
Rather than redevelop such a standard function.
Here's the related related manual page.
Can use as following in your case:
#include <string.h>
char *token;
token = strtok (string, " \r\n");
// do something with your first token
while (token != NULL)
{
// do something with subsequents tokens
token = strtok (NULL, " \r\n");
}
As you can observe, each subsequent call to strtok using the same arguments will send you back a char* adressing to the next token.
In the case you're working on a threaded program, you might use strtok_r() C function.
First call to it should be the same as strtok(), but subsequent calls are done passing NULL as the first argument. :
#include <string.h>
char *token;
char *saveptr;
token = strtok_r(string, " \r\n", &saveptr)
// do something with your first token
while (token != NULL)
{
// do something with subsequents tokens
token = strtok_r(NULL, " \r\n", &saveptr)
}
Just put the process token logic into aif(counter > 0){...}, which makes malloc happen only when there was a real token. like this
if(counter > 0){ // it means has a real word, not delimeters
char *output_token = malloc(counter+1);
strncpy(output_token,string+index,counter);
printf("%s \n", output_token);
TKProcessing(output_token);
}
I'm learning to use libcurl in C. To start, I'm using a randomized list of accession names to search for protein sequence files that may be found hosted here. These follow a set format where the first line is a variable length (but which contains no information I'm trying to query) then a series of capitalized letters with a new line every sixty (60) characters (what I want to pull down, but reformat to eighty (80) characters per line).
I have the call itself in a single function:
//finds and saves the fastas for each protein (assuming on exists)
void pullFasta (proteinEntry *entry, char matchType, FILE *outFile) {
//Local variables
URL_FILE *handle;
char buffer[2] = "", url[32] = "http://www.uniprot.org/uniprot/", sequence[2] = "";
//Build full URL
/*printf ("u:%s\nt:%s\n", url, entry->title); /*This line was used for debugging.*/
strcat (url, entry->title);
strcat (url, ".fasta");
//Open URL
/*printf ("u:%s\n", url); /*This line was used for debugging.*/
handle = url_fopen (url, "r");
//If there is data there
if (handle != NULL) {
//Skip the first line as it's got useless info
do {
url_fread(buffer, 1, 1, handle);
} while (buffer[0] != '\n');
//Grab the fasta data, skipping newline characters
while (!url_feof (handle)) {
url_fread(buffer, 1, 1, handle);
if (buffer[0] != '\n') {
strcat (sequence, buffer);
}
}
//Print it
printFastaEntry (entry->title, sequence, matchType, outFile);
}
url_fclose (handle);
return;
}
With proteinEntry being defined as:
//Entry for fasta formatable data
typedef struct proteinEntry {
char title[7];
struct proteinEntry *next;
} proteinEntry;
And the url_fopen, url_fclose, url_feof, url_read, and URL_FILE code found here, they mimic the file functions for which they are named.
As you can see I've been doing some debugging with the URL generator (uniprot URLs follow the same format for different proteins), I got it working properly and can pull down the data from the site and save it to file in the proper format that I want. I set the read buffer to 1 because I wanted to get a program that was very simplistic but functional (if inelegant) before I start playing with things, so I would have a base to return to as I learned.
I've tested the url_<function> calls and they are giving no errors. So I added incremental printf calls after each line to identify exactly where the bus error is occurring and it is happening at return;.
My understanding of bus errors is that it's a memory access issue wherein I'm trying to get at memory that my program doesn't have control over. My confusion comes from the fact that this is happening at the return of a void function. There's nothing being read, written, or passed to trigger the memory error (as far as I understand it, at least).
Can anyone point me in the right direction to fix my mistake please?
EDIT: As #BLUEPIXY pointed out I had a potential url_fclose (NULL). As #deltheil pointed out I had sequence as a static array. This also made me notice I'm repeating my bad memory allocation for url, so I updated it and it now works. Thanks for your help!
If we look at e.g http://www.uniprot.org/uniprot/Q6GZX1.fasta and skip the first line (as you do) we have:
MNAKYDTDQGVGRMLFLGTIGLAVVVGGLMAYGYYYDGKTPSSGTSFHTASPSFSSRYRY
Which is a 60 characters string.
When you try to read this sequence with:
//Grab the fasta data, skipping newline characters
while (!url_feof (handle)) {
url_fread(buffer, 1, 1, handle);
if (buffer[0] != '\n') {
strcat (sequence, buffer);
}
}
The problem is sequence is not expandable and not large enough (it is a fixed length array of size 2).
So make sure to choose a large enough size to hold any sequence, or implement the ability to expand it on-the-fly.
My C Win32 application should allow passing a full command line for another program to start, e.g.
myapp.exe /foo /bar "C:\Program Files\Some\App.exe" arg1 "arg 2"
myapp.exe may look something like
int main(int argc, char**argv)
{
int i;
for (i=1; i<argc; ++i) {
if (!strcmp(argv[i], "/foo") {
// handle /foo
} else if (!strcmp(argv[i], "/bar") {
// handle /bar
} else {
// not an option => start of a child command line
break;
}
}
// run the command
STARTUPINFO si;
PROCESS_INFORMATION pi;
// customize the above...
// I want this, but there is no such API! :(
CreateProcessFromArgv(argv+i, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
// use startup info si for some operations on a process
// ...
}
I can think about some workarounds:
use GetCommandLine()
and find a substring corresponding to argv[i]
write something similar to ArgvToCommandLine() also mentioned in another SO question
Both of them lengthy and re-implement cumbersome windows command line parsing logic, which is already a part of CommandLineToArgvW().
Is there a "standard" solution for my problem? A standard (Win32, CRT, etc.) implementation of workarounds counts as a solution.
It's actually easier than you think.
1) There is an API, GetCommandLine() that will return you the whole string
myapp.exe /foo /bar "C:\Program Files\Some\App.exe" arg1 "arg 2"
2) CreateProcess() allows to specify the command line, so using it as
CreateProcess(NULL, "c:\\hello.exe arg1 arg2 etc", ....)
will do exactly what you need.
3) By parsing your command line, you can just find where the exe name starts, and pass that address to the CreateProcess() . It could be easily done with
char* cmd_pos = strstr(GetCommandLine(), argv[3]);
and finally: CreateProcess(NULL, strstr(GetCommandLine(), argv[i]), ...);
EDIT: now I see that you've already considered this option. If you're concerned about performance penalties, they are nothing comparing to process creation.
The only standard function which you not yet included in your question is PathGetArgs, but it do not so much. The functions PathQuoteSpaces and PathUnquoteSpaces can be also helpful. In my opinion the usage of CommandLineToArgvW in combination with the with GetCommandLineW is what you really need. The usage of UNICODE during the parsing of the command line is in my opinion mandatory if you want to have a general solution.
I solved it as follows: With your Visual Studio install you can find a copy of some of the standard code used to create the C library. In particular if you look in VC\crt\src\stdargv.c you will find the implementation of "wparse_cmdline" function which creates argc and argv from the result of GetCommandLineW API. I created an augmented version of this code which also created a "cmdv" array of pointers which pointed back into the original string at the place where each argv pointer begins. You can then act on argv arguments as you wish, and when you want to pass the "rest" on to CreateProcess you can just pass in cmdv[i] instead.
This solution has the advantages that is uses the exact same parsing code, still provides argv as usual, and allows you to pass on the original without needing to re-quote or re-escape it.
I have faced the same problems with you. The thing is, we don't need to parse the whole string, if we can separate the result of GetCommandLine(), then you can put them together afterwards.
According to Microsoft's documentation, you should consider only backslashes and quotes.
You can find their documents here.
And, then, you can call Solve to get the next parameter start point.
E.g.
"a b c" d e
First Part: "a b c"
Next Parameter Start: d e
I solved the examples in Microsoft documentation, so do worry about the compatibility.
By calling the Solve function recursively, you can get the whole argv array.
Here's the file test.c
#include <stdio.h>
extern char* Solve(char* p);
void showString(char *str)
{
char *end = Solve(str);
char *p = str;
printf("First Part: ");
while(p < end){
fputc(*p, stdout);
p++;
}
printf("\nNext Parameter Start: %s\n", p + 1);
}
int main(){
char str[] = "\"a b c\" d e";
char str2[] = "a\\\\b d\"e f\"g h";
char str3[] = "a\\\\\\\"b c d";
char str4[] = "a\\\\\\\\\"b c\" d e";
showString(str);
showString(str2);
showString(str3);
showString(str4);
return 0;
}
Running result are:
First Part: "a b c"
Next Parameter Start: d e
First Part: a\\b
Next Parameter Start: d"e f"g h
First Part: a\\\"b
Next Parameter Start: c d
First Part: a\\\\"b c"
Next Parameter Start: d e
Here's all the source code of Solve function, file findarg.c
/**
This is a FSM for quote recognization.
Status will be
1. Quoted. (STATUS_QUOTE)
2. Normal. (STATUS_NORMAL)
3. End. (STATUS_END)
Quoted can be ended with a " or \0
Normal can be ended with a " or space( ) or \0
Slashes
*/
#ifndef TRUE
#define TRUE 1
#endif
#define STATUS_END 0
#define STATUS_NORMAL 1
#define STATUS_QUOTE 2
typedef char * Pointer;
typedef int STATUS;
static void MoveSlashes(Pointer *p){
/*According to Microsoft's note, http://msdn.microsoft.com/en-us/library/17w5ykft.aspx */
/*Backslashes are interpreted literally, unless they immediately precede a double quotation mark.*/
/*Here we skip every backslashes, and those linked with quotes. because we don't need to parse it.*/
while (**p == '\\'){
(*p)++;
//You need always check the next element
//Skip \" as well.
if (**p == '\\' || **p == '"')
(*p)++;
}
}
/* Quoted can be ended with a " or \0 */
static STATUS SolveQuote(Pointer *p){
while (TRUE){
MoveSlashes(p);
if (**p == 0)
return STATUS_END;
if (**p == '"')
return STATUS_NORMAL;
(*p)++;
}
}
/* Normal can be ended with a " or space( ) or \0 */
static STATUS SolveNormal(Pointer *p){
while (TRUE){
MoveSlashes(p);
if (**p == 0)
return STATUS_END;
if (**p == '"')
return STATUS_QUOTE;
if (**p == ' ')
return STATUS_END;
(*p)++;
}
}
/*
Solve the problem and return the end pointer.
#param p The start pointer
#return The target pointer.
*/
Pointer Solve(Pointer p){
STATUS status = STATUS_NORMAL;
while (status != STATUS_END){
switch (status)
{
case STATUS_NORMAL:
status = SolveNormal(&p); break;
case STATUS_QUOTE:
status = SolveQuote(&p); break;
case STATUS_END:
default:
break;
}
//Move pointer to the next place.
if (status != STATUS_END)
p++;
}
return p;
}
I think it's actually harder than you think for a general case.
See What's up with the strange treatment of quotation marks and backslashes by CommandLineToArgvW.
It's ultimately up to the individual programs how they tokenize the command-line into an argv array (and even CommandLineToArgv in theory (and perhaps in practice, if what one of the comments said is true) could behave differently than the CRT when it initializes argv to main()), so there isn't even a standard set of esoteric rules that you can follow.
But anyway, the short answer is: no, there unfortunately is no easy/standard solution. You'll have to roll your own function to deal with quotes and backslashes and the like.