Ostream class of 3 output stream objects Cout,cerr,clog differences and usage

the Ostream class defines 3 output Stream objects:cout,cerr,clog.

Cerr and clog are standard error streams, the difference is:cerr not through the buffer directly to the display output information;Clog In the buffer, when the buffer is full or Endl output to the monitor.

Example: Solve a two-time equation, if the formula error, with cerr flow output information.

Solution : Program:

#include <iostream>

#include <cmath>

using namespace Std;

int main ()

{

Float A, B, C, disc;

cout << "Please input a,b,c:";

Cin >> a >> b >> c;

if (a = = 0)

{

Cerr << "A is equal to zero,error!" << Endl;

}

else if ((disc = B*b-4*a*c) < 0)

{

Cerr << "disc = b*b-4*a*c< 0,error!" << Endl;

}

Else

{

cout << "x1=" << (-B + sqrt (disc))/(2 * a) << Endl;

cout << "x2=" << (-b-sqrt (disc))/(2 * a) << Endl;

}

System ("pause");

return 0;

}

Run result 1:

Please input a,b,c:0 2 3

A is equal to zero,error!

Please press any key to continue ...

Run result 2:

Please input A,b,c:5 2 3

Disc = b*b-4*a*c< 0,error!

Please press any key to continue ...

Run result 3:

Please input A,b,c:1 2.5 1.5

X1=-1

x2=-1.5

Please press any key to continue ...

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Ostream class of 3 output stream objects Cout,cerr,clog differences and usage