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

char *strrcat(char *str, char *sub){
    while(*str!='\0'){
        *str++;
    }
    while(*sub!='\0'){
        *str = *sub;
        *str++;
        *sub++;
    }
    *str++ = 't';//in this case use *str = '\0' its fine
    *str = 'z';
    *(str+1) = '\0';
    
    return str;
}

int main(){
    char str[20] = "Hi ";
    char sub[8] = "adarsh";
    
    strrcat(str,sub);
    printf("%s %ld",str,strlen(str));
}

#if 0
char *strcat(char *dest, const char *src) {
    //imp thing is we are copying dest address to originalDest
    
    //so when we retun oreginal dest we return addess of str1
    
    //not that necessary
    char *originalDest = dest; // Store the original destination pointer

    // Move the destination pointer to the end of the string
    while (*dest)
        dest++;

    // Append the source string to the destination
    while (*src)
        *(dest++) = *(src++);

    // Null-terminate the resulting concatenated string
    *dest = ' ';
    *(dest+1) = 'Y';//imp
    *(dest+2) = '\0';

    return originalDest;
}

int main() {
    char str1[20] = "Hello, ";//vimp since we need to give here extra space
    const char *str2 = "world!";//this becomes readonly !!!

    strcat(str1, str2);
    printf("%s\n", str1);

    return 0;
}
#endif