The cerr and clog streams direct output to standard error.
cerr provides unbuffered output, while clog provides buffered
output. The following example checks for a division by zero
condition. If one occurs, a message is sent to standard error.
/**
** Check for a division by zero condition.
** If one occurs, a message is sent to standard error.
**/
#include <iostream.h>
void main()
{
double val1, val2;
cout << "Divide Two Values" << endl;
cout << "Enter two numeric values: " << endl;
cin >> val1 >> val2;
if (val2 == 0 )
{
cerr << "The second value must be non-zero" << endl;
} else
cout << "The answer is " << val1 / val2 << endl;
}