Another Simple C++ Question

[iccaros]

how do I clear the screen.. I would like my programs to run on a clean screen, is there a clear in c++, must be .. I know I just use clear in bash??

thanks

[iccaros]

ok found it..

system ("clear");

but is there a more portable way as clear is linux but must be changed to cls for winders.??

thanks

Edited April 5, 2005 by iccaros

[jcl]

The only portable way is to blast enough newlines through the output stream to scroll away anything that might be there.

[iccaros]

hmmm.. ok.. well I'll just comment so I know where to change before I port.. thanks.

[jcl]

hmmm.. ok.. well I'll just comment so I know where to change before I port.. thanks.

Heh. The idiomatic way to deal with this sort of thing is to use conditional compilation via preprocessor guards.

void clear_screen()
{
#if defined WIN32
    system("cls");
#elif defined UNIX
    system("clear");
#endif
}

The preprocessor will insert the code corresponding to the first branch of the conditional that tests true (or will remove the code for the false branches, depending on how you look at it). When the source file is compiled you have to compiler define which ever symbol fits the current platform. For Linux/GCC you would use something like

$ gcc -DUNIX foo.c

Normally you'd set up the makefile to handle platform selection. Still requires some work for each build (unless you use something like autoconf or hack together your own platform detector) but at least it's reduced to a single edit in an obvious enough place.

Edited April 5, 2005 by jcl

[iccaros]

ok I follow..

I already have g++ foo.c -o foo

so to add -DUNIX is no big deal... It bash script anyways enter program to be compiled.. exe name.. so on...

I'm lazy and some time its easy to do ./compile foo.c and the bashscript does the rest.. so I could just add it to the script.

I am happy I found the systme command as now my installer is makeing better progress..

[iccaros]

ok .. I don't understand . I thought I would call it as a funcion.. am I missing something

// This is a test program
#include <iostream>
#include <iomanip>

void clear_screen()
{
#if defined WIN32
   system("cls");
#elif defined UNIX
   system("clear");
#endif
}


using namespace std;

int main ()
{
        int grade, total, gradeCounter;
        double average;

        total = 0;
        gradeCounter = 0;

        clear_screen;

        cout << "Enter Grade or -1 to finish ";
        cin >> grade;

while ( grade != -1) {
        total += grade;
        ++gradeCounter;

        cout << "Enter Grade or -1 to finish ";
        cin >> grade;
}

if ( gradeCounter != -1) {

        average = static_cast< double > ( total ) / gradeCounter;

        if ( average >= 60 )
                cout << "you pass!! with a grade point average of: " << average  << setprecision( 2 ) << fixed << endl;
        else
                cout << " You Failed!! with a Grade point average of: " << average << setprecision( 2 ) << fixed << endl;
}

else
        cout << "You did not enter any Grades!!!!" << endl;

return 0;
}

[iccaros]

I think posting makes my brain work add () after clear_screen...

and change if ( gradeCounter != -1 )

to if (gradeCounter != 0)

I will learn this...

Edited April 5, 2005 by iccaros