String.indexOf function in C

Question

Is there a C library function that will return the index of a character in a string?

So far, all I\'ve found are functions like strstr that will return the found cha

Answer 1

strstr returns a pointer to the found character, so you could use pointer arithmetic: (Note: this code not tested for its ability to compile, it's one step away from pseudocode.)

char * source = "test string";         /* assume source address is */
                                       /* 0x10 for example */
char * found = strstr( source, "in" ); /* should return 0x18 */
if (found != NULL)                     /* strstr returns NULL if item not found */
{
  int index = found - source;          /* index is 8 */
                                       /* source[8] gets you "i" */
}

Answer 2

You can write

s="bvbrburbhlkvp";
int index=strstr(&s,"h")-&s;

to find the index of 'h' in the given garble.

Answer 3

If you are not totally tied to pure C and can use string.h there is strchr() See here

Answer 4

Write your own :)

Code from a BSD licensed string processing library for C, called zString

https://github.com/fnoyanisi/zString

int zstring_search_chr(char *token,char s){
    if (!token || s=='\0')
        return 0;

    for (;*token; token++)
        if (*token == s)
            return 1;

    return 0;
}

Answer 5

EDIT: strchr is better only for one char. Pointer aritmetics says "Hellow!":

char *pos = strchr (myString, '#');
int pos = pos ? pos - myString : -1;

Important: strchr () returns NULL if no string is found

Answer 6

You can use strstr to accomplish what you want. Example:

char *a = "Hello World!";
char *b = strstr(a, "World");

int position = b - a;

printf("the offset is %i\n", position);

This produces the result:

the offset is 6