Function with two regular parameters and one parameter with default value : default arguments « Function « C++ Tutorial

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2. Function
3. default arguments

#include <iostream> 
#include <cstring> 
using namespace std; 
 
void f(char *s1, char *s2, int len = 0); 
 
int main() 
{ 
  char str1[80] = "This is a test"; 
  char str2[80] = "0123456789"; 
 
  f(str1, str2, 5); 
  f(str1, str2); 
  return 0; 
} 
 
void f(char *s1, char *s2, int len) 
{ 
  cout << s1;
  cout << " " << len << " "; 
  cout << s2;
}

This is a test 5 0123456789This is a test 0 0123456789