std::basic_ios::fail

1	`bool` `fail()` `const;`

Returns true if an error has occurred on the associated stream. Specifically, returns true if badbit or failbit is set in rdstate().

See ios_base::iostate for the list of conditions that set failbit or badbit.

Parameters

(none).

Return value

true if an error has occurred, false otherwise.

Example

#include <iostream>
#include <fstream>
#include <cstdlib>
int main()
{
    std::ifstream file("test.txt");
    if(!file)  // operator! is used here
    {  
        std::cout << "File opening failed\n";
        return EXIT_FAILURE;
    }
  
    // typical C++ I/O loop uses the return value of the I/O function
    // as the loop controlling condition, operator bool() is used here
    for(int n; file >> n; ) {
       std::cout << n << ' ';
    }
    std::cout << '\n';
  
    if (file.bad())
        std::cout << "I/O error while reading\n";
    else if (file.eof())
        std::cout << "End of file reached successfully\n";
    else if (file.fail())
        std::cout << "Non-integer data encountered\n";
}

`ios_base::iostate` flags			`basic_ios` accessors
eofbit	failbit	badbit	`good()`	`fail()`	`bad()`	`eof()`	`operator bool`	`operator!`
false	false	false	true	false	false	false	true	false
false	false	true	false	true	true	false	false	true
false	true	false	false	true	false	false	false	true
false	true	true	false	true	true	false	false	true
true	false	false	false	false	false	true	true	false
true	false	true	false	true	true	true	false	true
true	true	false	false	true	false	true	false	true
true	true	true	false	true	true	true	false	true

ferror

checks for a file error
(function)

Links:

http://en.cppreference.com/w/cpp/io/basic_ios/fail

doc_CPP

2025-01-10 15:47:30

Comments

std::basic_ios::fail

Parameters

Return value

Example

See also