Programming Forums > Application Development > C++

coldDeath · Aug 21st, 2005, 5:36 PM

Still not working, the if statement is going false, i don't know why.
here is my code:

#include <iostream>
#include <cstdlib>
using namespace std;

class cobra{
	public:
		cobra();
		~cobra();
	protected:
		int checkcommand(string n);
		string command;
};

cobra::cobra(){
	string command;
	while(1){
		cout<<">>> ";
		getline(cin, command);
		checkcommand(command);
	}
}
cobra::~cobra(){
}
int cobra::checkcommand(string n){
	if(command == "print hello"){
		cout<<"Hello";
		exit(0);
	}else{
		cout<<"Error";
		exit(1);
	}
}
int main(){
	cobra cobra1;
	return 0;
}

Polyphemus_ · Aug 21st, 2005, 5:38 PM

what's going false exactly? also remember, comparing strings is case sensitive.

EDIT:
noticed your mistake

(Toggle Plain Text)

int cobra::checkcommand(string n){
	if(n == "print hello"){
		cout<<"Hello";
		exit(0);
	}else{
		cout<<"Error";
		exit(1);
	}
}

coldDeath · Aug 21st, 2005, 5:41 PM

Waheeeey it worked.
It wouldv'e taken me a while to notice that as i'm tired.
Also welcome to the forums

Polyphemus_ · Aug 21st, 2005, 5:42 PM

Quote:

Originally Posted by coldDeath

Also welcome to the forums

Thanks

Arevos · Aug 21st, 2005, 5:45 PM

I'll show you the problem. It has a lot to do with scoping; you assign your getline string to a variable local to the function, rather than the object:

(Toggle Plain Text)

cobra::cobra(){
	string command;
	while(1){
		cout<<">>> ";
		getline(cin, command);
		checkcommand(command);
	}
}

Remove the "string command" line in this function.

coldDeath · Aug 21st, 2005, 5:49 PM

ok thank you, Welcome to the forums to you aswell

Ooble · Aug 22nd, 2005, 1:10 PM

To whoever recommended the exit function (I cannot be bothered to look up): don't use it. Using exit as opposed to exiting an application normally is akin to stopping a car by driving it into a brick wall. While it does exit the application, that's all it does. Any deconstructors that should be called at the end of the function will not be. If you've allocated memory, it won't be deallocated. Use exit as a last resort.

(the car analogy shamelessly stolen from Rick Rothstein on comp.lang.basic.visual)

OpenLoop · Aug 22nd, 2005, 1:18 PM

Quote:

Originally Posted by Ooble

To whoever recommended the exit function (I cannot be bothered to look up): don't use it. Using exit as opposed to exiting an application normally is akin to stopping a car by driving it into a brick wall. ...

I knew Ooble would want to comment on the exit() function. I agree with you, never use exit(1) unless you're implementing an emergency shutdown button for a WMD missle launcher

.

coldDeath · Aug 22nd, 2005, 1:41 PM

lol, thanks i was wondering how to make that button.

What sort of alternative can i use to exit();?

Polyphemus_ · Aug 22nd, 2005, 1:48 PM

Quote:

Originally Posted by coldDeath

lol, thanks i was wondering how to make that button.

What sort of alternative can i use to exit();?

i'd say to break all the loops. You can define a variable, which you set to false when there is an error. All the loops check this variable, and if it is false, you break (or return).

Aug 21st, 2005, 5:36 PM	#11
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	Still not working, the if statement is going false, i don't know why. here is my code: (Toggle Plain Text) #include <iostream> #include <cstdlib> using namespace std; class cobra{ public: cobra(); ~cobra(); protected: int checkcommand(string n); string command; }; cobra::cobra(){ string command; while(1){ cout<<">>> "; getline(cin, command); checkcommand(command); } } cobra::~cobra(){ } int cobra::checkcommand(string n){ if(command == "print hello"){ cout<<"Hello"; exit(0); }else{ cout<<"Error"; exit(1); } } int main(){ cobra cobra1; return 0; } #include <iostream> #include <cstdlib> using namespace std; class cobra{ public: cobra(); ~cobra(); protected: int checkcommand(string n); string command; }; cobra::cobra(){ string command; while(1){ cout<<">>> "; getline(cin, command); checkcommand(command); } } cobra::~cobra(){ } int cobra::checkcommand(string n){ if(command == "print hello"){ cout<<"Hello"; exit(0); }else{ cout<<"Error"; exit(1); } } int main(){ cobra cobra1; return 0; } __________________ 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.

Aug 21st, 2005, 5:38 PM	#12
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	what's going false exactly? also remember, comparing strings is case sensitive. EDIT: noticed your mistake (Toggle Plain Text) int cobra::checkcommand(string n){ if(n == "print hello"){ cout<<"Hello"; exit(0); }else{ cout<<"Error"; exit(1); } } int cobra::checkcommand(string n){ if(n == "print hello"){ cout<<"Hello"; exit(0); }else{ cout<<"Error"; exit(1); } }

Aug 21st, 2005, 5:41 PM	#13
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	Waheeeey it worked. It wouldv'e taken me a while to notice that as i'm tired. Also welcome to the forums __________________ 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.

Aug 21st, 2005, 5:45 PM	#15
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	I'll show you the problem. It has a lot to do with scoping; you assign your getline string to a variable local to the function, rather than the object: (Toggle Plain Text) cobra::cobra(){ string command; while(1){ cout<<">>> "; getline(cin, command); checkcommand(command); } } cobra::cobra(){ string command; while(1){ cout<<">>> "; getline(cin, command); checkcommand(command); } } Remove the "string command" line in this function.

Aug 21st, 2005, 5:49 PM	#16
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	ok thank you, Welcome to the forums to you aswell __________________ 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.

Aug 22nd, 2005, 1:10 PM	#17
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	To whoever recommended the exit function (I cannot be bothered to look up): don't use it. Using exit as opposed to exiting an application normally is akin to stopping a car by driving it into a brick wall. While it does exit the application, that's all it does. Any deconstructors that should be called at the end of the function will not be. If you've allocated memory, it won't be deallocated. Use exit as a last resort. (the car analogy shamelessly stolen from Rick Rothstein on comp.lang.basic.visual) __________________ Me :: You :: Them

Aug 22nd, 2005, 1:41 PM	#19
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	lol, thanks i was wondering how to make that button. What sort of alternative can i use to exit();? __________________ 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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Programming Forums > Application Development > C++

Exiting a program