Programming Forums > Script Programming > Python

coldDeath · Apr 17th, 2006, 5:13 AM

I really should know how to do this, but I had a break from programming for a while and got addicted to several MMORPGs and forgot a lot of stuff

.

But anyway, I was writing a simple program in a few languages to compare them and when I came to Python I thought it would be really easy, but I just couldn't do it

The program should just exit and return the value of the number of arguments that the program recieved at runtime.

Heres what I did in C++ and ASM:

(Toggle Plain Text)

--C++--
//returns the number of arguments that the program recieved at runtime.
int main(int argc, char* argv[])
{
	return argc-1;
}
--ASM--
;returns the number of arguments that the program recieved at runtime.
section .data

section .text
	global _start

	_start:
		pop ebx 
		dec ebx 
		mov eax,1
		int 80h

So when I looked at Python, I knew that the number of arguments was stored in sys.argc. So I have to return sys.argc.

Thats where I got stuck, (yes this is really simple but I completely forgot how to do it) I need to know how to return the value as an exit code like in the previous examples.

It can be tested by running the program with arguments, then running "echo $?".

Thanks for you help.

~Cold

Arevos · Apr 17th, 2006, 5:24 AM

Use sys.exit and len(sys.argv):

(Toggle Plain Text)

import sys
sys.exit(len(sys.argv) - 1)

coldDeath · Apr 17th, 2006, 5:43 AM

Ah thanks thats what I needed. Why do you need to call the len() method on sys.argc? I thought it held an integer value.

Cerulean · Apr 17th, 2006, 7:34 AM

There is no sys.argc. Just sys.argv, which is an array of arguments passed to the application. Calling len on the argument list will give you the number of arguments.

Sane · Apr 17th, 2006, 8:33 AM

If you ever get stuck on something like that, and you know what module it's in try running help(sys) and looking for the description of what you're trying to do.

Arevos · Apr 17th, 2006, 8:46 AM

C has argv and argc because C arrays don't contain information about their length. Python lists do, so the argc variable is superfluous.

coldDeath · Apr 17th, 2006, 9:09 AM

Ok I see, I was overlooking what you wrote in the code and didnt read it properly, I thought it said argc

Sane · Apr 17th, 2006, 10:02 AM

Arevos, do you know why your site won't work for me? I can view the source and see everything that should be there, but nothing will display in the browser... I've tried waiting and reloading several times.

coldDeath · Apr 17th, 2006, 12:05 PM

Quote:

Originally Posted by Sane

Arevos, do you know why your site won't work for me? I can view the source and see everything that should be there, but nothing will display in the browser... I've tried waiting and reloading several times.

This domain name expired on Mar 23, 2006.

Arevos · Apr 17th, 2006, 4:07 PM

Quote:

Originally Posted by Sane

Arevos, do you know why your site won't work for me? I can view the source and see everything that should be there, but nothing will display in the browser... I've tried waiting and reloading several times.

Curious. Could you tell me what browser and OS you're using? Also, have you tried forcing a refresh of all images, styles and scripts with "ctrl-refresh"? I'd really appreciate any information you could give me.

Quote:

Originally Posted by coldDeath

This domain name expired on Mar 23, 2006.

What on earth are you talking about? A quick whois confirms that the renewal date for monkeyengines.co.uk is 14-Oct-2006.

Apr 17th, 2006, 5:13 AM	#1
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	I really should know how to do this... I really should know how to do this, but I had a break from programming for a while and got addicted to several MMORPGs and forgot a lot of stuff. But anyway, I was writing a simple program in a few languages to compare them and when I came to Python I thought it would be really easy, but I just couldn't do it The program should just exit and return the value of the number of arguments that the program recieved at runtime. Heres what I did in C++ and ASM: (Toggle Plain Text) --C++-- //returns the number of arguments that the program recieved at runtime. int main(int argc, char* argv[]) { return argc-1; } --ASM-- ;returns the number of arguments that the program recieved at runtime. section .data section .text global _start _start: pop ebx dec ebx mov eax,1 int 80h --C++-- //returns the number of arguments that the program recieved at runtime. int main(int argc, char* argv[]) { return argc-1; } --ASM-- ;returns the number of arguments that the program recieved at runtime. section .data section .text global _start _start: pop ebx dec ebx mov eax,1 int 80h So when I looked at Python, I knew that the number of arguments was stored in sys.argc. So I have to return sys.argc. Thats where I got stuck, (yes this is really simple but I completely forgot how to do it) I need to know how to return the value as an exit code like in the previous examples. It can be tested by running the program with arguments, then running "echo $?". Thanks for you help. ~Cold __________________ Programming Tutorials - Linux Installation Guide - Learn Python - Learn C++ Got Slack? Join us at #programmingforums @ irc.freenode.net! My software never has bugs. It just develops random features.

Apr 17th, 2006, 5:24 AM	#2
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	Use sys.exit and len(sys.argv): (Toggle Plain Text) import sys sys.exit(len(sys.argv) - 1) import sys sys.exit(len(sys.argv) - 1)

Apr 17th, 2006, 5:43 AM	#3
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	Ah thanks thats what I needed. Why do you need to call the len() method on sys.argc? I thought it held an integer value. __________________ Programming Tutorials - Linux Installation Guide - Learn Python - Learn C++ Got Slack? Join us at #programmingforums @ irc.freenode.net! My software never has bugs. It just develops random features.

Apr 17th, 2006, 9:09 AM	#7
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	Ok I see, I was overlooking what you wrote in the code and didnt read it properly, I thought it said argc __________________ Programming Tutorials - Linux Installation Guide - Learn Python - Learn C++ Got Slack? Join us at #programmingforums @ irc.freenode.net! My software never has bugs. It just develops random features.

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Apr 17th, 2006, 7:34 AM	#4
Cerulean Professional Programmer Join Date: Apr 2005 Location: London, England Posts: 459 Rep Power: 4	There is no sys.argc. Just sys.argv, which is an array of arguments passed to the application. Calling len on the argument list will give you the number of arguments.

Apr 17th, 2006, 8:33 AM	#5
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,069 Rep Power: 6	If you ever get stuck on something like that, and you know what module it's in try running help(sys) and looking for the description of what you're trying to do.

Apr 17th, 2006, 8:46 AM	#6
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	C has argv and argc because C arrays don't contain information about their length. Python lists do, so the argc variable is superfluous.

Apr 17th, 2006, 10:02 AM	#8
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,069 Rep Power: 6	Arevos, do you know why your site won't work for me? I can view the source and see everything that should be there, but nothing will display in the browser... I've tried waiting and reloading several times.

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Programming Forums > Script Programming > Python

I really should know how to do this...