C++ basic_istream::putback()用法及代碼示例

basic_istream::putback()用於將字符放回輸入字符串中。 iostream頭文件中提供了此函數。以下是相同的語法：

頭文件：

#include<iostream>

用法:

basic_istream& putback (char_type ch);

參數：

ch:它表示要放回輸入字符串中的字符。

返回值：iostream::basic_istream::putback()返回basic_istream對象。

下麵的程序可以更好地了解std::basic_istream::putback()的實現：

程序1:

// C++ code for basic_istream::putback() 
#include <bits/stdc++.h> 
  
using namespace std; 
  
int main() 
{ 
    stringstream gfg1("GeeksforGeeks"); 
    gfg1.get(); 
  
    // putback A into the input string 
    if (gfg1.putback('A')) 
        cout << gfg1.rdbuf() << endl; 
  
    istringstream gfg2("GeeksforGeeks"); 
    gfg2.get(); 
  
    if (gfg2.putback('A')) 
        cout << gfg2.rdbuf() << endl; 
    else
        cout << "putback is failed here\n"; 
  
    gfg2.clear(); 
  
    // Again putback G in the string 
    if (gfg2.putback('G')) 
        cout << gfg2.rdbuf() << endl; 
}

輸出：

AeeksforGeeks
putback is failed here
GeeksforGeeks

程序2:

// C++ code for basic_istream::putback() 
#include <bits/stdc++.h> 
  
using namespace std; 
  
int main() 
{ 
    stringstream gfg1("GOOD"); 
    gfg1.get(); 
  
    // putback B into the input string 
    if (gfg1.putback('B')) 
        cout << gfg1.rdbuf() << endl; 
  
    istringstream gfg2("GOOD"); 
    gfg2.get(); 
  
    if (gfg2.putback('B')) 
        cout << gfg2.rdbuf() << endl; 
    else
        cout << "putback is failed here\n"; 
  
    gfg2.clear(); 
  
    // Again putback G in the string 
    if (gfg2.putback('G')) 
        cout << gfg2.rdbuf() << endl; 
}

輸出：

BOOD
putback is failed here
GOOD

參考：http://www.cplusplus.com/reference/istream/istream/putback/

相關用法

注：本文由純淨天空篩選整理自bansal_rtk_大神的英文原創作品 basic_istream::putback() in C++ with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。