#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char * buffer;

const char const * hello = "hello, ";
const char const * world = "world!";

int mystrlen( const char const * s ) { // measure length of string s
    int len = 0;
    while (s[len] != '\0') len ++;
    return len;
}

int main() {
    buffer = malloc( mystrlen(hello) + mystrlen(world) + 1 );
    strcpy(buffer,hello);
    strcat(buffer,world);
    puts(buffer);    /* output the accumulated text */
    return 0;
}