Returns whether the object is currently associated to a file (i.e., open).
The function returns true if a previous call to member open succeeded and there have been no calls to member close since.
Parameters
none
Return Value
true if a file is open and associated with this file stream buffer object. false otherwise.
Example
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// filebuf::is_open() example
#include <iostream>
#include <fstream>
int main () {
std::ifstream is;
std::filebuf * fb = is.rdbuf();
fb->open ("test.txt",std::ios::in);
if ( fb->is_open() )
std::cout << "the file is open.\n";
else
std::cout << "the file is not open.\n";
fb->close();
return 0;
}
Data races
Accesses the basic_filebuf object.
Concurrent access to the same file stream buffer object may introduce data races.
Exception safety
Strong guarantee: if an exception is thrown, there are no changes in the file stream buffer.