How do I find the index of a character within a string in C?

Question

Suppose I have a string \"qwerty\" and I wish to find the index position of the e character in it. (In this case the index would be 2)

Answer 1

void myFunc(char* str, char c)
{
    char* ptr;
    int index;

    ptr = strchr(str, c);
    if (ptr == NULL)
    {
        printf("Character not found\n");
        return;
    }

    index = ptr - str;

    printf("The index is %d\n", index);
    ASSERT(str[index] == c);  // Verify that the character at index is the one we want.
}

This code is currently untested, but it demonstrates the proper concept.