C++中的basic_istream :: peek()及其示例

std :: basic_istream :: peek()用于从输入流中读取下一个字符，而无需提取它。该函数不接受任何参数，仅返回输入字符串的下一个字符。以下是相同的语法：

头文件：

#include

句法：

int peek();

返回值： std :: basic_istream :: peek()返回输入字符串的下一个字符。

下面的程序可以更好地了解std :: basic_istream :: peek()的实现：

程序1：

// C++ code for std::basic_istream::peek()
#include 
using namespace std;
  
// main method
int main()
{
    istringstream gfg("GeeksforGeeks");
  
    char c1 = gfg.peek();
    char c2 = gfg.get();
    char c3 = gfg.get();
  
    cout << "The first character is: "
         << c1 << endl
         << " and the next is: "
         << c3 << endl;
}

输出：

The first character is: G 
and the next is: e

程式2：

// C++ code for std::basic_istream::peek()
#include 
using namespace std;
  
// main method
int main()
{
    istringstream gfg("Computer");
  
    char c1 = gfg.peek();
    char c2 = gfg.get();
    char c3 = gfg.get();
  
    cout << "The first character is: "
         << c1 << endl
         << " and the next is: "
         << c3 << endl;
}

输出：

The first character is: C 
and the next is: o

程序3：

// C++ code for std::basic_istream::peek()
#include 
using namespace std;
  
// main method
int main()
{
    istringstream gfg("Laptop");
  
    char c1 = gfg.peek();
    char c2 = gfg.get();
    char c3 = gfg.get();
    char c4 = gfg.get();
  
    cout << "The first character is: "
         << c1 << endl
         << " and the next is: "
         << c3 << endl
         << " after that next is: "
         << c4 << endl;
}

输出：

The first character is: L 
and the next is: a 
after that next is: p

参考： http : //www.cplusplus.com/reference/istream/basic_istream/peek/

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