📜  C++中的cout

📅  最后修改于: 2021-05-30 02:03:22             🧑  作者: Mango

C++中的cout对象是ostream类的对象。它在iostream头文件中定义。它用于显示输出到标准输出设备,即监视器。它与标准C输出流stdout相关联。使用插入运算符(<<)将需要在屏幕上显示的数据插入到标准输出流(cout)中。

程序1:

下面是实现cout对象的C++程序:

C++
// C++ program to illustrate the use
// of cout object
#include 
using namespace std;
  
// Driver Code
int main()
{
    // Print standard ouput
    // on the screen
    cout << "Welcome to GFG";
  
    return 0;
}


C++
// C++ program to illustrate printing
// of more than one statement in a
// single cout statement
#include 
using namespace std;
  
// Driver Code
int main()
{
    string name = "Akshay";
    int age = 18;
  
    // Print multiple variable on
    // screen using cout
    cout << "Name : " << name << endl
         << "Age : " << age << endl;
  
    return 0;
}


C++
// C++ program to illustrate the use
// of cout.write() and cout.put()
#include 
using namespace std;
  
// Driver Code
int main()
{
    char gfg[] = "Welcome at GFG";
    char ch = 'e';
  
    // Print first 6 characters
    cout.write(gfg, 6);
  
    // Print the character ch
    cout.put(ch);
    return 0;
}


C++
// C++ program toillustrate the use
// of cout.precision()
#include 
using namespace std;
  
// Driver Code
int main()
{
    double pi = 3.14159783;
  
    // Set precison to 5
    cout.precision(5);
  
    // Print pi
    cout << pi << endl;
  
    // Set precision to 7
    cout.precision(7);
  
    // Print pi
    cout << pi << endl;
  
    return 0;
}


输出:
Welcome to GFG

注意:使用带有cout的插入运算符(<<)可以打印多个变量。

程式2:

下面是实现上述方法的C++程序:

C++

// C++ program to illustrate printing
// of more than one statement in a
// single cout statement
#include 
using namespace std;
  
// Driver Code
int main()
{
    string name = "Akshay";
    int age = 18;
  
    // Print multiple variable on
    // screen using cout
    cout << "Name : " << name << endl
         << "Age : " << age << endl;
  
    return 0;
}
输出:
Name : Akshay
Age : 18

cout语句也可以与某些成员函数一起使用:

  • cout.write(char * str,int n):打印从str读取的前N个字符。
  • cout.put(炭&CH):打印存储在字符ch的字符。
  • cout.precision(int n):使用浮点值时,将小数精度设置为N。

程序3:

以下是cout.write()cout.put()的成员函数的实现:

C++

// C++ program to illustrate the use
// of cout.write() and cout.put()
#include 
using namespace std;
  
// Driver Code
int main()
{
    char gfg[] = "Welcome at GFG";
    char ch = 'e';
  
    // Print first 6 characters
    cout.write(gfg, 6);
  
    // Print the character ch
    cout.put(ch);
    return 0;
}
输出:
Welcome

计划4:

下面是C++程序,用于说明cout.precision()用法

C++

// C++ program toillustrate the use
// of cout.precision()
#include 
using namespace std;
  
// Driver Code
int main()
{
    double pi = 3.14159783;
  
    // Set precison to 5
    cout.precision(5);
  
    // Print pi
    cout << pi << endl;
  
    // Set precision to 7
    cout.precision(7);
  
    // Print pi
    cout << pi << endl;
  
    return 0;
}
输出:
3.1416
3.141598
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