std::basic_ios<CharT,Traits>::good

 

C++

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std::basic_ios

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basic_ios::basic_ios

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basic_ios::good

basic_ios::eof

basic_ios::fail

basic_ios::bad

basic_ios::operator!

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bool good()const;

Returns true if the most recent I/O operation on the stream completed successfully. Specifically, returns result of rdstate()==0.

See ios_base::iostate for the list of conditions that set the stream status bits.

Parameters

(none)

Return value

true if the stream error flags are all false, false otherwise.

Example

Run this code

#include <cstdlib>#include <fstream>#include <iostream>   int main(){constchar* fname ="/tmp/test.txt";std::ofstream ofile{fname}; ofile <<"10 "<<"11 "<<"12 "<<"non-int"; ofile.close();   std::ifstream file{fname};if(!file.good()){std::cout<<"#1. Opening file test.txt failed - ""one of the error flags is true\n";returnEXIT_FAILURE;}   // typical C++ I/O loop uses the return value of the I/O function// as the loop controlling condition, operator bool() is used herefor(int n; file >> n;)std::cout<< n <<' ';std::cout<<'\n';   if(file.bad()){std::cout<<"#2. I/O error while reading - badbit is true\n";returnEXIT_FAILURE;}elseif(file.eof())std::cout<<"#3. End of file reached successfully - eofbit is true\n""This is fine even though file.good() is false\n";elseif(file.fail())std::cout<<"#4. Non-integer data encountered - failbit is true\n";}

Possible output:

10 11 12 #4. Non-integer data encountered - failbit is true

See also

The following table shows the value of basic_ios accessors (good(), fail(), etc.) for all possible combinations of ios_base::iostate flags:

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