Get the beginning of a string until a given char

Question

I know that is a simple question but I couldn't find the answer.

I have this string:

"M1[r2][r3]"

I want to get only the "M1", I'm looking for something like strchr() a function that get the string and a char to stop at.

Answer 1

What about using strtok and "[" as a delimiter?

#include <string.h> /* for strtok */
#include <stdio.h>  /* for printf */
int main()
{
    char str[] = "M1[r2][r3]"; // str will be modified by strtok
    const char deli[] = "[";   // deli could also be declared as [2] or as const char *. Take your pick...
    char *token;

    token = strtok(str, deli); // can also call strtok(str, "["); and not use variable deli at all
    printf("%s", token);       // printf("%s", str); will print the same result

    /* OUTPUT: M1 */

    return 0;    
}

Answer 2

Use strtok() and the character to stop (a delimeter, in your case [) like this:

#include <stdio.h>
#include <string.h>

int main ()
{
  char str[] ="M1[r2][r3]";
  printf ("Getting M1 from \"%s\":\n",str);
  strtok (str,"[");
  if (str != NULL)
    printf ("%s\n",str);
  return 0;
}

Output:

Getting M1 from "M1[r2][r3]":
M1

---

However, if you know the length of the substring, you should see Get a substring of a char*.

Answer 3

something like strchr() a function that get the string and a char to stop at.

If only a printing of the sub-string is needed, use strcspn() which finds the offset when '[' first occurs, (or the end if not found). This does not alter the source string.

const char *s = "M1[r2][r3]";
printf("%.*s\n", (int) strcspn(s, "["), s);

Output

M1

Answer 4

Use sscanf() like this:

char subStr[3];
sscanf("M1[r2][r3]", " %2[^[]", subStr);

where [^[] means a character except [ and 2 guards the length of the string written into the substring (it's equal to subStr's size - 1, so that space for the NULL terminator is available).

as BLUEPIXY suggested.