c++ - overloading << and using namespace std -


i need understanding following:

i overloaded << operator. wrote test program. didnt include "using namespace std" code. program worked out well. 

#include <iostream> #include "fraction.h"  //using namespace std;  int main(void) { //constructing 2 fractions     fraction a(4, 2);     fraction b(17, 11); //modifying them entering fractions keyboard     cin>>a;     cin>>b; //computing product , quotient , printing them using cout     cout<<a*b<<endl;     cout<<a/b<<endl; }

but can see used "endl" standard namespace. can explain me "paradox" m getting here.

p.s didnt include .h , .cpp file because think irrelevant.

when #include something, straight text replacement file. since #include "fraction.h" , has line

using namespace std;

the main file uses std.

also note, not practice using namespace std; in header files since everywhere else includes header automatically use std can cause conflicts if programmer unaware.


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