std::basic_fstream::is_open
bool is_open(); | ? | (until C++11) |
|---|---|---|
bool is_open() const; | ? | (since C++11) |
检查文件流是否有关联的文件。
有效呼叫rdbuf()->is_open()...
参数
%280%29
返回值
true如果文件流有关联的文件，false否则。
例
二次
#include <string>
#include <fstream>
#include <iostream>
int main()
{
std::string filename = "some_file";
std::fstream fs(filename, std::ios::in);
std::cout << std::boolalpha;
std::cout << "fs.is_open() = " << fs.is_open() << '\n';
if(!fs.is_open())
{
fs.clear();
fs.open(filename, std::ios::out);
std::cout << "fs.is_open() = " << fs.is_open() << '\n';
}
}二次
可能的产出：
二次
fs.is_open() = false
fs.is_open() = true二次
另见
open | opens a file and associates it with the stream (public member function) |
|---|---|
close | closes the associated file (public member function) |
? cppreference.com在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。
本文档系腾讯云开发者社区成员共同维护，如有问题请联系 cloudcommunity@tencent.com
