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C++ Question ...

Fender2112

Fender2112

macrumors 65816
Original poster
Aug 11, 2002
1,144
417
Charlotte, NC
In my c++ class I've been exposed to these commands:

system("cls") which clears the screen.
system("pause") which envokes the 'Press any key to continue' command.

I informed my instructor that these commands don't work on my Mac. He told me that these are DOS commands.

My question: What are the Mac OS equivalents to these?

Thanks much.
 
There really aren't any equivalents.

I'm guessing that you're using these to show your output clearly in the DOS Window.

You can probably code these as:

#ifdef __MSDOS__
system("cls");
#endif

...

#ifdef __MSDOS__
system("pause");
#endif

They will execute on the DOS/Windows machines but work without error on Mac OS X or most anything else as well.

To execute the programme within Mac OS X, you would open the Terminal application and type ./programme-name and press <return> or <enter>.
 
Re: C++ Question ...

Originally posted by Fender2112
In my c++ class I've been exposed to these commands:

system("cls") which clears the screen.
system("pause") which envokes the 'Press any key to continue' command.

I informed my instructor that these commands don't work on my Mac. He told me that these are DOS commands.

My question: What are the Mac OS equivalents to these?

Thanks much.
Click to expand...

system("clear"); // clear the screen
system("echo -n Press ENTER to continue. ; echo $<"); // pause for input

should get you going, if you are using the default tcsh shell. Try these from the command line and then work them into the code.
 
I tried both of these suggestions but neither worked.

Here's the code I'm using with CodeWarrior:


//***************************************************************************************
//* This program uses a two dimensional arrary to store the hours worked for five days *
//* for five employees. The user enters the hours worked each day for each employee. *
//* A daily average is calculated for the five day period for each employee. *
//***************************************************************************************


int main ()
{

float hoursWorked [5] [5]; // Two dimensional array with five elements in each dimension
float totHours, dayAvg;


for (int emp = 1; emp <= 5; emp ++) // This loop sets first index of the array
{
//*** I need to clear the screen here ***
system("cls");
system ("clear");

totHours = 0; // reset totals for each employee
dayAvg = 0;


cout.precision(2); // Use this and
cout.setf(ios::fixed | ios::showpoint); // this to set decimal precision

cout << "Enter the hours workd each day for employee: " << emp << endl;

for (int day = 1; day <= 5; day ++) // This loop sets the second index of the array
{
cout << "How many hours did this employee work on day " << day << ": ";
cin >> hoursWorked [emp] [day];
totHours = totHours + hoursWorked [emp] [day];
}

// Calculate the daily average for this employee
dayAvg = totHours / 5;
cout << "This employee has a daily average of " << dayAvg << " hours.";
cout << endl << endl;

//*** I need to pause here ***
system("pause");
system("echo -n Press ENTER to continue. ; echo $<"); // pause for input


}

return 0;
}

//*** End Program ***
 
Well, you can't use them quite that way. Instead of

system("cls");
system ("clear");

use

#ifdef __MSDOS__
system("cls");
#else
system ("clear");
#endif

Make the same type of change further down. Those are two underscores in front and in back of MSDOS. If __MSDOS__ doesn't work, you might try __WINDOWS__
 
Originally posted by Fender2112
I tried both of these suggestions but neither worked.

Here's the code I'm using with CodeWarrior:


//***************************************************************************************
//* This program uses a two dimensional arrary to store the hours worked for five days *
//* for five employees. The user enters the hours worked each day for each employee. *
//* A daily average is calculated for the five day period for each employee. *
//***************************************************************************************


int main ()
{

float hoursWorked [5] [5]; // Two dimensional array with five elements in each dimension
float totHours, dayAvg;


for (int emp = 1; emp <= 5; emp ++) // This loop sets first index of the array
{
//*** I need to clear the screen here ***
system("cls");
system ("clear");

totHours = 0; // reset totals for each employee
dayAvg = 0;


cout.precision(2); // Use this and
cout.setf(ios::fixed | ios::showpoint); // this to set decimal precision

cout << "Enter the hours workd each day for employee: " << emp << endl;

for (int day = 1; day <= 5; day ++) // This loop sets the second index of the array
{
cout << "How many hours did this employee work on day " << day << ": ";
cin >> hoursWorked [emp] [day];
totHours = totHours + hoursWorked [emp] [day];
}

// Calculate the daily average for this employee
dayAvg = totHours / 5;
cout << "This employee has a daily average of " << dayAvg << " hours.";
cout << endl << endl;

//*** I need to pause here ***
system("pause");
system("echo -n Press ENTER to continue. ; echo $<"); // pause for input


}

return 0;
}

//*** End Program ***
Click to expand...

You don't need the dos cls command.
// system("cls");

Pause by doing the same thing the previous code is doing:

cout << "Press ENTER to continue.";
cin >> reply;

Obviously, you need to add a variable for the reply.

Get rid of the system calls for pause.

Fixing the remaining bugs is an exercise for the author.....
 
Originally posted by bousozoku
Well, you can't use them quite that way. Instead of

system("cls");
system ("clear");

use

#ifdef __MSDOS__
system("cls");
#else
system ("clear");
#endif

Make the same type of change further down. Those are two underscores in front and in back of MSDOS. If __MSDOS__ doesn't work, you might try __WINDOWS__
Click to expand...

These don't work, unless I'm doing something wrong. Which is highly possible.
 
Originally posted by db2guru
You don't need the dos cls command.
// system("cls");

Pause by doing the same thing the previous code is doing:

cout << "Press ENTER to continue.";
cin >> reply;

Obviously, you need to add a variable for the reply.

Get rid of the system calls for pause.

Fixing the remaining bugs is an exercise for the author.....
Click to expand...

Pausing is not the problem. It's the continue part. I still have to input something for the cin statement. C++ does not acknowledge a "null" entry. At least not to my limited knowledge.

I'm sure there is a simple solution to this. I hate to think that there is actually something this simple that can be done on Windows but not a Mac. Please tell me it ain't so.:(
 
Originally posted by Fender2112
Pausing is not the problem. It's the continue part. I still have to input something for the cin statement. C++ does not acknowledge a "null" entry. At least not to my limited knowledge.
Click to expand...
For the "pause" part of the code, see if this works better instead:

Code: 
#include <stdio.h>

int main()
{
    ...
    // Pause and wait for a keypress before going on
    printf("Press any key to continue...");
    getchar();
    printf("\n");

    // Now continue...
}
 
Originally posted by Lyle
For the "pause" part of the code, see if this works better instead:

Code: 
#include <stdio.h>

int main()
{
    ...
    // Pause and wait for a keypress before going on
    printf("Press any key to continue...");
    getchar();
    printf("\n");

    // Now continue...
}
Click to expand...

Okay, that got me pointed in the right direction. I came up with this, which is within the scope of what I've learned in my class.

cout << "Press ENTER to continue.";
cin.get(); // clears white space from input buffer
getline (cin, wait); // wait is declared as a string type
cout << endl;

It's not as nice system("pause"), but it works for my purposes at the moment.

Now, how about that clear screen command? Any ideas.
 
Originally posted by Fender2112
Now, how about that clear screen command? Any ideas?
Click to expand...
Doing
Code: 
system("clear");
didn't work? I just tried a quickie little test program and it had the desired effect here.
 
Originally posted by Lyle
Doing
Code: 
system("clear");
didn't work? I just tried a quickie little test program and it had the desired effect here.
Click to expand...

Nope. It doesn't work for me. I'm using CodeWarrior 5.0 Learning Edition. What compiler are you using? Do I need a header file for system("clear")?
 
Originally posted by Fender2112
Nope. It doesn't work for me. I'm using CodeWarrior 5.0 Learning Edition. What compiler are you using?
Click to expand...
I'm using gcc (which comes free with the Apple Developer Tools).
Do I need a header file for system("clear")?
Click to expand...
Well, technically you should include <stdlib.h> at the top of the file, but if it's compiling without errors that's probably not the source of your problem.
 
Originally posted by db2guru
Try these from the command line and then work them into the code.
Click to expand...
Fender2112: Try running your program from the Terminal command prompt. Open the Termina, cd to your program's directory, and execute the program from there.

Running the program from within CodeWarrior (yes, I know it's a "console" application) is not likely the same as running it from the command line. It depends on the implementation of "console" by your compiler.
 
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