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std::basic_string::empty

性病：基本[医]字符串：空

bool empty() const;​​

检查字符串是否没有字符，即是否begin() == end()...

参数

%280%29

返回值

true如果字符串是空的，false否则。

例外

(none)(until C++11)
noexcept specification: noexcept(since C++11)

复杂性

常量。

例

二次

#include <iostream>
#include <string>
 
int main()
{
    std::string s;
    std::boolalpha(std::cout
    std::cout << "s.empty():" << s.empty() << "\t s:'" << s << "'\n";
 
    s = "Exemplar";
    std::cout << "s.empty():" << s.empty() << "\t s:'" << s << "'\n";
 
    s = "";
    std::cout << "s.empty():" << s.empty() << "\t s:'" << s << "'\n";
}

二次

产出：

二次

s.empty():true         s:''
s.empty():false         s:'Exemplar'
s.empty():true         s:''

二次

另见

sizelengthreturns the number of characters (public member function)

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