public member function
<string>

std::basic_string::empty

bool empty() const;
bool empty() const noexcept;
Test whether string is empty
Returns whether the basic_string is empty (i.e. whether its length is0).

This function does not modify the value of the string in any way. To clear the content of a basic_string, see basic_string::clear.

参数



返回值

trueif the string length is0, false否则为 false。

示例

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// string::empty
#include <iostream>
#include <string>

int main ()
{
  std::string content;
  std::string line;
  std::cout << "Please introduce a text. Enter an empty line to finish:\n";
  do {
    getline(std::cin,line);
    content += line + '\n';
  } while (!line.empty());
  std::cout << "The text you introduced was:\n" << content;
  return 0;
}

This program reads the user input line by line and stores it into stringcontentuntil an empty line is introduced.

复杂度

未指定,但通常是恒定的。
常量。

迭代器有效性

没有变化。

数据竞争

该对象被访问。

异常安全

无异常保证:此成员函数从不抛出异常。

另见