#include <stdlib.h>
#include <stdio.h>

char *my_weirddup(char *src){

    if(src == NULL) return NULL;

    int index = 0;
    while(*(src)){
        index ++;
        src ++;
    }
    
    char *str =  malloc(index + 1);
    if(str == NULL) return NULL; 
    
    //src = 0;
    
    char lettre = ' ';
    index = 0;
    
    while (*src){
        lettre = *src;

        //maj
        if (lettre > 64 && lettre < 91){
            if (lettre == 'Z') lettre = 'A';
            else lettre += 1;
        }

        //min
        else if (lettre > 97 && lettre < 124 ){
            
            if (lettre == 'z')lettre = 'a';
            else lettre += 1;    
        }

        *str = lettre;
        src ++;
        str ++;
    }

    return str;
}

int main(){

    printf("%s",my_weirddup("abb"));

}