are_all_string_characters_different.c

/*

    are_all_string_characters_different.c

    Are all characters in string different from each other.
    Check if all characters in string are distinct (unique).
    Check if string contains all unique or distinct characters.


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

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

// returns 1 if all characters in string are distinct (unique, different from each other)
// otherwise returns 0
int are_all_string_characters_different( char str[] )
{
    int i, j, len = strlen(str);

    for (i=0; i<len; i++)
        for (j=i+1; j<len; j++)
            if (str[i] == str[j])
                return 0;

    return 1;
}


int main(void)
{
    char str1[] = "String 1";
    char str2[] = "Second string";

    printf("\n str1 = \"%s\" \n", str1);

    if ( are_all_string_characters_different(str1) )
        printf("\n All string characters are distinct (unique, different from each other). \n");
    else
        printf("\n There are repeating characters in the string. \n");

    printf("\n str2 = \"%s\" \n", str2);

    if ( are_all_string_characters_different(str2) )
        printf("\n All string characters are distinct (unique, different from each other). \n");
    else
        printf("\n There are repeating characters in the string. \n");

    return 0;

} // main()