C Program- How do you find the index of any character in a string? [closed]

Question

For example, in a string, you'll be asked to find and print the index of a capital character:

char str[100] = "helloWorld";

the capital letter is found at index 5 so printf("Index of capital letter: Index %d") in which %d should be 5

How do you create a code to print the index?

Answer 1

Use strcspn():

Synopsis

1

    #include <string.h>
    size_t strcspn(const char *s1, const char *s2);

Description

2 The strcspn function computes the length of the maximum initial segment of the string pointed to by s1 which consists entirely of characters not from the string pointed to by s2.

Returns

3 The strcspn function returns the length of the segment.

For example:

// get the index of the first upper-case character
// return ( ssize_t ) -1 if there are none
ssize_t firstUpperCase( const char *str )
{
    ssize_t index = strcspn( str, "ABCDEFGHIJKLMNOPQRSTUVWXYZ" );
    if ( index >= strlen( str )
    {
        index = ( ssize_t ) -1;
    }
    return( index );
}

Answer 2

To locate the first uppercase letter in the string, you must use a loop:

#include <ctype.h>
#include <stdio.h>

int main() {
    char str[100] = "helloWorld";
    for (int i = 0; str[i] != '\0'; i++) {
        if (isupper((unsigned char)str[i]) {
            printf("Index of capital letter '%c': %d\n", str[i], i);
            return 0;
        }
    }
    printf("No capital letter\n");
    return 1;
}