uni-m.cds-adv-prog/ex1.3/join_strings.cpp

#include <iostream>
#include <string.h>

// join will return a pointer of type 'char'
char* join(const char*, const char*) ;
char* joinb(const char*, const char*) ;


int main()
{
	std::cout << join("alpha","bet") << std::endl ;
	std::cout << joinb("duck","soup") << std::endl ;
	
	return 0 ;
}

/* this function is owner of new_str,
 * since it doesn't delete it, there is leakage
 */

char* join(const char* str1 , const char* str2)
{
	/* use 'new' because we don't know how big the strings are going to be
	 * the length should be 'strlen(str1) + strlen(str2) + 1'
	 *  since strlen does not count the null bytes we need to add one
	 */

	int size = strlen(str1) + strlen(str2) + 1;

	char* new_str = new char[size];
	*new_str =  0; // Null String

	strcat(new_str, str1); // new_str = 0 + str1
	strcat(new_str, str2); // new_str = new_str + str2

	return new_str;

}

char* joinb(const char* str1 , const char* str2)
{
	// size should be 2 more than required for the strlens to 
	// incorporate the space and the null byte
	int size = strlen(str1) + strlen(str2) + 2;

	char* new_str = new char[size];
	*new_str =  0;

	strcat(new_str, str1);
	strcat(new_str, " "); // insert space, note it is important to have it as a string => \"
	strcat(new_str, str2);

	return new_str;

}