这里没有提到的两点我认为很重要:

1)如果你还没有使用STL, cout会携带很多包袱。它向目标文件中添加的代码是printf的两倍多。对于字符串也是如此，这也是我倾向于使用自己的字符串库的主要原因。

2) cout使用重载的<<操作符，我觉得这很不幸。如果还将<<运算符用于其预期目的(左移)，则会增加混淆。我个人不喜欢为了与其预期用途无关的目的而重载操作符。

底线:如果我已经在使用STL，我将使用cout(和字符串)。否则，我倾向于避免它。

更多的差异: "printf"返回一个整数值(等于打印的字符数)，"cout"不返回任何东西

And.

Cout << "y = " << 7;不是原子的。

Printf ("%s = %d"， "y"， 7);是原子的。

Cout执行类型检查，printf不执行。

iostream中没有% d的等价物

我引用一下:

在高层术语中，主要的区别是类型安全(cstdio 没有它)，性能(大多数iostreams实现都有 比cstdio慢)和可扩展性(iostreams允许 自定义输出目标和用户定义类型的无缝输出)。

我想指出的是，如果你想在c++中使用线程，如果你使用cout，你可以得到一些有趣的结果。

考虑下面的代码:

#include <string>
#include <iostream>
#include <thread>

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

现在，输出都被打乱了。它也可以产生不同的结果，试着执行几次:

##12::  ABABAB

##12::  ABABAB

##12::  ABABAB

##12::  ABABAB

##12::  ABABAB

你可以使用printf，也可以使用互斥。

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

玩得开心!

Printf是一个函数而cout是一个变量。

来自c++常见问题解答:

[15.1] Why should I use <iostream> instead of the traditional <cstdio>? Increase type safety, reduce errors, allow extensibility, and provide inheritability. printf() is arguably not broken, and scanf() is perhaps livable despite being error prone, however both are limited with respect to what C++ I/O can do. C++ I/O (using << and >>) is, relative to C (using printf() and scanf()): More type-safe: With <iostream>, the type of object being I/O'd is known statically by the compiler. In contrast, <cstdio> uses "%" fields to figure out the types dynamically. Less error prone: With <iostream>, there are no redundant "%" tokens that have to be consistent with the actual objects being I/O'd. Removing redundancy removes a class of errors. Extensible: The C++ <iostream> mechanism allows new user-defined types to be I/O'd without breaking existing code. Imagine the chaos if everyone was simultaneously adding new incompatible "%" fields to printf() and scanf()?! Inheritable: The C++ <iostream> mechanism is built from real classes such as std::ostream and std::istream. Unlike <cstdio>'s FILE*, these are real classes and hence inheritable. This means you can have other user-defined things that look and act like streams, yet that do whatever strange and wonderful things you want. You automatically get to use the zillions of lines of I/O code written by users you don't even know, and they don't need to know about your "extended stream" class.

另一方面，printf要快得多，因此在非常特定和有限的情况下，可以优先使用它而不是cout。总是先做侧写。(例如，参见http://programming-designs.com/2009/02/c-speed-test-part-2-printf-vs-cout/)