Is there a function in c that will return the index of a char in a char array?

Question

Is there a function in c that will return the index of a char in a char array?

For example something like:

char values[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char find = 'E';

int index = findInedexOf( values, find );

Answer 1

strchr()

Answer 2

strchr returns the pointer to the first occurrence, so to find the index, just take the offset with the starting pointer. For example:

char values[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char find = 'E';

const char *ptr = strchr(values, find);
if(ptr) {
   int index = ptr - values;
   // do something
}

Answer 3

What about strpos?

#include <string.h>

int index;
...
index = strpos(values, find);

Note that strpos expects a zero-terminated string, which means you should add a '\0' at the end. If you can't do that, you're left with a manual loop and search.

Answer 4

int index = strchr(values,find)-values;

Note, that if there's no find found, then strchr returns NULL, so index will be negative.

Answer 5

You can use strchr to get a pointer to the first occurrence and the subtract that (if not null) from the original char* to get the position.

Answer 6

There's also size_t strcspn(const char *str, const char *set); it returns the index of the first occurence of the character in s that is included in set:

size_t index = strcspn(values, "E");