Programming Forums > Application Development > C++

Da-Kid · Feb 14th, 2005, 10:55 PM

#include <iostream>
#include <cstdlib>

using namespace std;

int main()
{

        system( "echo Date: `date`" );
        system( "echo Uptime: `uptime`" );
        system( "echo Name: `uname -n`" );
        system( "echo Kernel: `uname -r`" );
}

I run this program with the command ./sysinfo
But I want to be able to add flags for instance ./sysinfo -d prints only the date line, can someone tell me how to make that possible? And also I found a line in bash that displays the hdd space.

(Toggle Plain Text)

 df | awk '{ sum+=\$2/1024^2 }; END { printf (\"%dGb\", sum 
             )}

Can someone tell me how to turn that into C++ code?

Mjordan2nd · Feb 14th, 2005, 11:04 PM

You're going to need to declare main like this:

(Toggle Plain Text)

 int main(int argc, char *argv[])

where argc is the number of arguments that are passed from the command line, and argv is a string representation of an argument. So for instance, in your -d example, argc would be 2 (I believe), since their are two arguments (the name of your program and "-d"), and argv[1] would be "-d".

Da-Kid · Feb 14th, 2005, 11:19 PM

(Toggle Plain Text)

#include <iostream>
#include <cstdlib>

using namespace std;
         
int main(int argc, char *argv[2])
{        
        
        system( "echo Date: `date`" );
        system( "echo Uptime: `uptime`" );
        system( "echo Name: `uname -n`" );
        system( "echo Kernel: `uname -r`" );
}

So with that code above, if I run ./sysinfo -d it'll only print the Date line?

Mjordan2nd · Feb 14th, 2005, 11:45 PM

You would need some if statements.

And main would have to be declared as such:

(Toggle Plain Text)

int main(int argc, char *argv[])

And then, if you want to use the -d flag or something you could do something like this:

(Toggle Plain Text)

 if(strcmp(argv[2], "-d") == 0)
 {
 	 // print out date
 }

Keep in mind, strcmp() is in the string.h header file.

Also, just for your info, you could also declare main like this:

(Toggle Plain Text)

int main(int argc, char **argv)

but I've never done it like that. I always use the method I posted before. Also, the argument names could be changed to best suit your needs, argc and argv are just customary, though.

Da-Kid · Feb 15th, 2005, 12:28 AM

You kinda lost me, but I tried the code

(Toggle Plain Text)

#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{

        system( "echo Date: `date`" );
        system( "echo Uptime: `uptime`" );
        system( "echo Name: `uname -n`" );
        system( "echo Kernel: `uname -r`" );

        if(strcmp(argv[2], "-d") == 0)
        {
                system( "echo Date: `date`" );
        }
}

And as a result I got

(Toggle Plain Text)

c0debox programming # ./sysinfo -d
Date: Tue Feb 15 00:26:13 EST 2005
Uptime: 00:26:13 up 2:33, 4 users, load average: 0.07, 0.08, 0.06
Name: c0debox
Kernel: 2.6.10
Segmentation fault

Mjordan2nd · Feb 15th, 2005, 12:43 AM

I appologize. It should be argv[1]. I don't know what I was thinking.

Anyway, here's code for you:

(Toggle Plain Text)

  #include <iostream>
  #include <string.h>
  #include <stdio.h>
  
  using namespace std;
  
  int main(int argc, char *argv[])
  {	
  	if(argc>1)
  	{
  		if(strcmp(argv[1], "-d") == 0)
  		{
      			    system( "echo Date: `date`" );
  		}
  	}		
  	else
  	{
  		system( "echo Date: `date`" );	
  		system( "echo Uptime: `uptime`" );
  		system( "echo Name: `uname -n`" );
  		 system( "echo Kernel: `uname -r`" );
  	}
  
  		
  }

Da-Kid · Feb 15th, 2005, 1:22 AM

Cool it worked. Now can you explain this line for me so I can set the flags up for everything else

(Toggle Plain Text)

  	if(argc>1)
  	{
  		if(strcmp(argv[1], "-d") == 0)
  		{
      			    system( "echo Date: `date`" );
  		}

Da-Kid · Feb 15th, 2005, 5:57 AM

(Toggle Plain Text)

// Written by c0demuncher

#include <iostream>
#include <string>

using namespace std;

void c0de()
{
        system( "echo Date: `date`" );
        system( "echo Uptime: `uptime`" );
        system( "echo Name: `uname -n`" );
        system( "echo CPU: `uname -p`" );
        system( "echo Kernel: `uname -r`" );
}

int main(int argc, char *argv[])
{
        if(argc>1)
        {
                if(strcmp(argv[1], "-d") == 0)
                {
                        system( "echo Date: `date`" );
                }
        }
        else
        {
                 c0de();
        }
}

Thats my updated code, but I'm not sure where to add that if statement to add more flags, and what exactly that if statement means

Berto · Feb 15th, 2005, 7:00 AM

To be honest with you, you need to go back to the fundementals of programming looking at if statements, string handlers loops etc etc before you get into this because if you had read about arrays and if statements this would be a breeze for you.

Mjordan2nd · Feb 15th, 2005, 7:46 AM

if(argc>1) means if there's more than one argument passed from main. Everytime you leave a space when calling a program, and then add another string after the name of the program, you're passing arguments to it. The first argument is the name of the program, the second argument is, in this case, "-d." argc just counts arguments.

if(strcmp(argv[1], "-d") == 0)

means if argv[1] (argument passed from main) is -d then you do whatever code that follows.

Feb 14th, 2005, 10:55 PM	#1
Da-Kid Programmer Join Date: Nov 2004 Posts: 47 Rep Power: 0	System Info (Toggle Plain Text) #include <iostream> #include <cstdlib> using namespace std; int main() { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); } #include <iostream> #include <cstdlib> using namespace std; int main() { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); } I run this program with the command ./sysinfo But I want to be able to add flags for instance ./sysinfo -d prints only the date line, can someone tell me how to make that possible? And also I found a line in bash that displays the hdd space. (Toggle Plain Text) df \| awk '{ sum+=\$2/1024^2 }; END { printf (\"%dGb\", sum )} df \| awk '{ sum+=\$2/1024^2 }; END { printf (\"%dGb\", sum )} Can someone tell me how to turn that into C++ code?

Feb 14th, 2005, 11:04 PM	#2
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	You're going to need to declare main like this: (Toggle Plain Text) int main(int argc, char argv[]) int main(int argc, char argv[]) where argc is the number of arguments that are passed from the command line, and argv is a string representation of an argument. So for instance, in your -d example, argc would be 2 (I believe), since their are two arguments (the name of your program and "-d"), and argv[1] would be "-d". __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Feb 14th, 2005, 11:19 PM	#3
Da-Kid Programmer Join Date: Nov 2004 Posts: 47 Rep Power: 0	(Toggle Plain Text) #include <iostream> #include <cstdlib> using namespace std; int main(int argc, char argv[2]) { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); } #include <iostream> #include <cstdlib> using namespace std; int main(int argc, char argv[2]) { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); } So with that code above, if I run ./sysinfo -d it'll only print the Date line?

Feb 14th, 2005, 11:45 PM	#4
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	You would need some if statements. And main would have to be declared as such: (Toggle Plain Text) int main(int argc, char argv[]) int main(int argc, char argv[]) And then, if you want to use the -d flag or something you could do something like this: (Toggle Plain Text) if(strcmp(argv[2], "-d") == 0) { // print out date } if(strcmp(argv[2], "-d") == 0) { // print out date } Keep in mind, strcmp() is in the string.h header file. Also, just for your info, you could also declare main like this: (Toggle Plain Text) int main(int argc, char argv) int main(int argc, char argv) but I've never done it like that. I always use the method I posted before. Also, the argument names could be changed to best suit your needs, argc and argv are just customary, though. __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Feb 15th, 2005, 12:28 AM	#5
Da-Kid Programmer Join Date: Nov 2004 Posts: 47 Rep Power: 0	You kinda lost me, but I tried the code (Toggle Plain Text) #include <iostream> using namespace std; int main(int argc, char argv[]) { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); if(strcmp(argv[2], "-d") == 0) { system( "echo Date: `date`" ); } } #include <iostream> using namespace std; int main(int argc, char argv[]) { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); if(strcmp(argv[2], "-d") == 0) { system( "echo Date: `date`" ); } } And as a result I got (Toggle Plain Text) c0debox programming # ./sysinfo -d Date: Tue Feb 15 00:26:13 EST 2005 Uptime: 00:26:13 up 2:33, 4 users, load average: 0.07, 0.08, 0.06 Name: c0debox Kernel: 2.6.10 Segmentation fault c0debox programming # ./sysinfo -d Date: Tue Feb 15 00:26:13 EST 2005 Uptime: 00:26:13 up 2:33, 4 users, load average: 0.07, 0.08, 0.06 Name: c0debox Kernel: 2.6.10 Segmentation fault

Feb 15th, 2005, 12:43 AM	#6
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	I appologize. It should be argv[1]. I don't know what I was thinking. Anyway, here's code for you: (Toggle Plain Text) #include <iostream> #include <string.h> #include <stdio.h> using namespace std; int main(int argc, char argv[]) { if(argc>1) { if(strcmp(argv[1], "-d") == 0) { system( "echo Date: `date`" ); } } else { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); } } #include <iostream> #include <string.h> #include <stdio.h> using namespace std; int main(int argc, char argv[]) { if(argc>1) { if(strcmp(argv[1], "-d") == 0) { system( "echo Date: `date`" ); } } else { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo Kernel: `uname -r`" ); } } __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Feb 15th, 2005, 1:22 AM	#7
Da-Kid Programmer Join Date: Nov 2004 Posts: 47 Rep Power: 0	Cool it worked. Now can you explain this line for me so I can set the flags up for everything else (Toggle Plain Text) if(argc>1) { if(strcmp(argv[1], "-d") == 0) { system( "echo Date: `date`" ); } if(argc>1) { if(strcmp(argv[1], "-d") == 0) { system( "echo Date: `date`" ); }

Feb 15th, 2005, 5:57 AM	#8
Da-Kid Programmer Join Date: Nov 2004 Posts: 47 Rep Power: 0	(Toggle Plain Text) // Written by c0demuncher #include <iostream> #include <string> using namespace std; void c0de() { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo CPU: `uname -p`" ); system( "echo Kernel: `uname -r`" ); } int main(int argc, char argv[]) { if(argc>1) { if(strcmp(argv[1], "-d") == 0) { system( "echo Date: `date`" ); } } else { c0de(); } } // Written by c0demuncher #include <iostream> #include <string> using namespace std; void c0de() { system( "echo Date: `date`" ); system( "echo Uptime: `uptime`" ); system( "echo Name: `uname -n`" ); system( "echo CPU: `uname -p`" ); system( "echo Kernel: `uname -r`" ); } int main(int argc, char argv[]) { if(argc>1) { if(strcmp(argv[1], "-d") == 0) { system( "echo Date: `date`" ); } } else { c0de(); } } Thats my updated code, but I'm not sure where to add that if statement to add more flags, and what exactly that if statement means

Feb 15th, 2005, 7:00 AM	#9
Berto Programming Guru Join Date: Aug 2004 Posts: 1,022 Rep Power: 6	To be honest with you, you need to go back to the fundementals of programming looking at if statements, string handlers loops etc etc before you get into this because if you had read about arrays and if statements this would be a breeze for you.

Feb 15th, 2005, 7:46 AM	#10
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	if(argc>1) means if there's more than one argument passed from main. Everytime you leave a space when calling a program, and then add another string after the name of the program, you're passing arguments to it. The first argument is the name of the program, the second argument is, in this case, "-d." argc just counts arguments. if(strcmp(argv[1], "-d") == 0) means if argv[1] (argument passed from main) is -d then you do whatever code that follows. __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

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Programming Forums > Application Development > C++

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