basic_istream :: putback()用于将字符放回输入字符串。 iostream头文件中提供了此函数。以下是相同的语法:
头文件:
#include
句法:
basic_istream& putback (char_type ch);
范围:
- CH:它代表被放入输入字符串后面的字符。
返回值: iostream :: basic_istream :: putback()返回basic_istream对象。
下面的程序可以更好地了解std :: basic_istream :: putback()的实现:
程序1:
// C++ code for basic_istream::putback()
#include
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;
}
输出:
AeeksforGeeks
putback is failed here
GeeksforGeeks
程式2:
// C++ code for basic_istream::putback()
#include
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;
}
输出:
BOOD
putback is failed here
GOOD
参考: http : //www.cplusplus.com/reference/istream/istream/putback/
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