编程导航

C++

语法

基础

方法1

  调用库：

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#include <iostream>

调用函数：

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std::cout << "Hello!\n";

方法2

  命名空间，省略 std。

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#include <iostream>
using namespace std;

调用函数：

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cout << "Hello!\n";

组合方式

组合方式1

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std::cout << "Hello World!\n";

组合方式2

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std::cout << "Hello" << " World!\n";

组合方式3

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std::cout << "Hello";
std::cout << " World!\n";

特殊符号

回车

  回车表示将光标移动到行的开头。这应该和键盘上的回车有所区分。

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std::cout << "\r";

换行

  换行表示将光标移动到下一行的开头。

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std::cout << "\n";

或者：

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std::cout << std::endl;

变量调用

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int num = 100;
std::cout << "数字是：" << num << std::endl;
std::string st = "你好，世界！";
std::cout << st << std::endl;

演示

  演示效果如下：

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#include <iostream>

int main()
{
    std::cout << "Print\n";
    std::cout << "|_" << "语法\n";
    std::cout << "| |_" << "基础\n";
    std::cout << "| | |_" << "Hello!\n";
    std::cout << "| |" << "\n";
    std::cout << "| |_" << "组合方式\n";
    std::cout << "| | |_" << "组合方式1\n";
    std::cout << "| | | |_" << "Hello World!\n";
    std::cout << "| | |" << "\n";
    std::cout << "| | |_" << "组合方式2\n";
    std::cout << "| | | |_" << "Hello" << " World!\n";
    std::cout << "| | |" << "\n";
    std::cout << "| | |_" << "组合方式3\n";
    std::cout << "| |   |_" << "Hello"; std::cout << " World!\n";
    std::cout << "| |" << "\n";
    std::cout << "| |_" << "特殊符号\n";
    std::cout << "| | |_" << "回车\n";
    std::cout << "| |   |_" << "\r"; std::cout << "*\n";
    std::cout << "| | |_" << "换行\n";
    std::cout << "| |   |_" << "\n"; std::cout << "*\n";
    std::cout << "| |   |_" << "或者\n"; 
    std::cout << "| |   |_" << std::endl; std::cout << "*\n";
    std::cout << "| |" << "\n";
    std::cout << "| |_" << "变量调用\n";
    int num = 100;
    std::cout << "| | |_" << "数字是：" << num << std::endl;
    std::string st = "你好，世界！";
    std::cout << "| | |_" << st << std::endl;
}

说明：换行和回车有明显区别。

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#include <iostream>
using namespace std;

int main()
{
    // 有三处可以省略 std::
    string st = "你好，世界！";
    cout << st << endl;
}