string functions in C++

/*
strlen(str) returns length of the string str.
strcpy(str1,str2) copy the string from the str2 to str1.
strcat(str1,str2) catenate str1 to str2.
*/


#include <iostream>
#include<conio>
#include<cstring>
void main ()
{
   char str1[10] = "Hello";
   char str2[10] = "World";
   char str3[10];
   int  len ;

   // copy str1 into str3
   strcpy( str3, str1);
   cout << "strcpy( str3, str1) : " << str3 << endl;

   // concatenates str1 and str2
   cout << "strcat( str1, str2): " <<   strcat( str1, str2)<< endl;

   // total lenghth of str1 after concatenation
   len = strlen(str1);
   cout << "strlen(str1) : " << len << endl;

   getch();
}

Output