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std::basic_ifstream::is_open

性病：基本[医]如果流：：is[医]开着的营业的

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>
//this file is called main.cpp
 
bool file_exists(const std::string& str)
{
   std::ifstream fs(str
   return fs.is_open(
}
 
int main()
{
  std::boolalpha(std::cout
  std::cout << file_exists("main.cpp")  << '\n'
            << file_exists("strange_file") << '\n';
}

二次

可能的产出：

二次

true
false

二次

另见

openopens a file and associates it with the stream (public member function)
closecloses the associated file (public member function)

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