stcuk in loop

This is a discussion on stcuk in loop within the C++ Programming forums, part of the General Programming Boards category; why is my program stuck in the last while loop? compile this code.. then enter 3,4,5 for a,b,c and then ...

  1. #1
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    stcuk in loop

    why is my program stuck in the last while loop? compile this code.. then enter 3,4,5 for a,b,c and then enter "y'' for your choice to continue... it continues to loop forever

    Code:
    #include <iostream.h>
    #include <math.h>
    #include <string.h>
    
    int main ()
    {
    	double a, b, c, s, area, perimeter, choice;
    	do
    	{
    	do
    	{
    		cout << "Enter side a of the triangle: ";
    		cin >> a;
    		while (a <= 0)
    		{
    			cout << "The sides of a triangle must be greater than 0." <<endl;
    			cout << "Please enter a number greater than 0: ";
    			cin >> a;
    		}
    		cout << "Enter side b of the triangle: "; 
    		cin >> b;
    		while (b <= 0)
    		{
    			cout << "The sides of a triangle must be greater than 0." <<endl;
    			cout << "Please enter a number greater than 0: ";
    			cin >> b;
    		}
    		cout << "Enter side c of the triangle: ";
    		cin >> c;
    		while (c <= 0)
    		{
    			cout << "The sides of a triangle must be greater than 0." <<endl;
    			cout << "Please enter a number greater than 0: ";
    			cin >> c;
    		}
    		if (a+b<c || a+c<b || b+c<a)
    		{
    			cout << "That is not a valid triangle." <<endl;
    			cout << "Please re-enter three sides: " <<endl;
    		}
    		
    	}
    	while(a+b<c || a+c<b || b+c<a);
    	
    	perimeter= a+b+c;
    	cout << "The perimeter is: " << perimeter <<endl;
    	s=(a+b+c)/2;
    	area= sqrt(s*(s-a)*(s-b)*(s-c));
    	if (area==0)
    		cout << "The area cannot be zero." <<endl;
    	else
    		cout << "The area is: " << area <<endl;
    	cout << "Do you want to try again?" <<endl;
    	cout << "Choose [Y/N]" <<endl;
    	cin >> choice;
    	while (choice != 'y' && choice != 'Y' && choice != 'n' && choice != 'N'){
    			cout << "I do not understand. Try again: ";
    			cin >> choice;
    		}
    	} while (c == 'y' || c == 'Y');
    	return 0;
    	cin.ignore(); cin.ignore();
    }

  2. #2
    C++まいる!Cをこわせ! Elysia's Avatar
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    Because choice is a double and y is a char.
    Btw, indent properly. Makes code easier to read.

  3. #3
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    edit: I'm wrong. Thanks Elysia.
    Code:
    while(a+b<c || a+c<b || b+c<a);
    this loop? it's an infinite loop. the conditional never changes.
    Last edited by robwhit; 11-11-2007 at 11:18 PM.

  4. #4
    C++まいる!Cをこわせ! Elysia's Avatar
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    No, the syntax is correct - it's a do...while loop.

  5. #5
    Algorithm Dissector iMalc's Avatar
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    You're not handling some cases of invalid triangles such as 1, 2, 4.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

  6. #6
    Its hard... But im here swgh's Avatar
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    incidently, try using more discriptive variable names rather than a,b,c etc. it stands out better what they represent and makes reading and espcially debugging the code a lot easier.
    I'm just trying to be a better person - My Name Is Earl

  7. #7
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    Although in this case, a, b and c are commonly used names for the sides of the triangle, and they are even used in the prompts for their values, so it's not that bad. The variable s, on the other hand, doesn't seem to be as self-explanatory.

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