'printf' vs. 'cout' in C++

Question

What is the difference between printf() and cout in C++?

Answer 1

I'd like to point out that if you want to play with threads in C++, if you use cout you can get some interesting results.

Consider this code:

#include 
#include 
#include 

using namespace std;

void task(int taskNum, string msg) {
    for (int i = 0; i < 5; ++i) {
        cout << "#" << taskNum << ": " << msg << endl;
    }
}

int main() {
    thread t1(task, 1, "AAA");
    thread t2(task, 2, "BBB");
    t1.join();
    t2.join();
    return 0;
}

// g++ ./thread.cpp -o thread.out -ansi -pedantic -pthread -std=c++0x

Now, the output comes all shuffled. It can yield different results too, try executing several times:

##12::  ABABAB

##12::  ABABAB

##12::  ABABAB

##12::  ABABAB

##12::  ABABAB

You can use printf to get it right, or you can use mutex.

#1: AAA
#2: BBB
#1: AAA
#2: BBB
#1: AAA
#2: BBB
#1: AAA
#2: BBB
#1: AAA
#2: BBB

Have fun!