C++ LANGUAGE STANDARD LOG STREAM (CLOG)

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C++ LANGUAGE STANDARD LOG STREAM (CLOG)

 
The Standard Log Stream (clog) 


The predefined object clog is an instance of ostream class. 
The clog object is said to be attached to the standard error 
device, which is also a display screen but the object clog is 
buffered. This means that each insertion to clog could cause 
its output to be held in a buffer until the buffer is filled 
or until the buffer is flushed. 

The clog is also used in conjunction with the stream insertion 
operator as shown in the following example. 

#include <iostream> 
  
using namespace std; 
  
int main( ) 
{ 
   char str[] = "Unable to read...."; 
  
   clog << "Error message : " << str << endl; 
} 
When the above code is compiled and executed, 
it produces the following result: 

Error message : Unable to read.... 

You would not be able to see any difference in cout, cerr 
and clog with these small examples, but while writing and 
executing big programs the difference becomes obvious. 
So it is good practice to display error messages using cerr 
stream and while displaying other log messages then clog should be used.