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Old 10-08-2005, 08:30 PM   #1
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Registered: Oct 2005
Posts: 14

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having trouble with the do while loop in program

my program compiles but doesn't ever move past the do/ while loop.

#include <iostream>

#include <cstdlib>

#include <cmath>

using namespace std;

int main(void)

int atHome=0, stepsToTry=5000, home, start, steps=0;
double x, y, dx, dy, angle;
const int minx = -10;
const int maxx = 10;
const int miny = -10;
const int maxy = 10;
const double PI = 4*atan(1.0);

cout << "Will Waldo make it home? \n\n";

cout << "Input an int to start the random number generator: ";
int myStart;
cin >> myStart;

home = (((x>=8) && (x<=10)) && ((y>=8) && (y<=10)));
start = ((x = 0) && (y = 0));

for (stepsToTry = 5000; stepsToTry>0; stepsToTry = stepsToTry - 1)
steps = steps + 1;
angle = 2*PI*rand()/RAND_MAX;
dx = cos(angle);
dy = sin(angle);

while (((dx>=-10) && (dx<=10)) && ((dy>=-10) && (dy<=10)));
start = (dx && dy);
if (start == home)



if (atHome=1)
cout<< "Waldo made it home in "<<steps<<"! \n\n";
else if (steps = 5000)
cout<<"Waldo is still lost after taking 5000 steps \n\n";

return 0;

Old 10-08-2005, 10:05 PM   #2
LQ Guru
Registered: Mar 2004
Distribution: SusE 8.2
Posts: 5,863
Blog Entries: 1

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Two questions:
1. What kind of debugger do you have available to step through and see if dx and dy are being incremented the way you think they are?
(Hint: will they EVER be incremented to a value that will cause the loop to exit)?

2. Could you please familiarize yourself with the LQ "[code]" tags, to help make your code more legible?

Thanx in advance .. PSM

Last edited by paulsm4; 10-08-2005 at 10:07 PM.
Old 10-08-2005, 10:18 PM   #3
Registered: Jun 2005
Location: Indiana, USA
Distribution: OpenBSD, Ubuntu
Posts: 892

Rep: Reputation: 43
do {...} while(...);

I think there might be a problem with the way you've constructed your do/while loop; you have a code block underneath the while statement that doesn't do anything except change the scope of "start". It looks like you might have intended the block to be part of a while loop, but do/while works like this:
do {
Also, just by glancing over it, you're doing some weird stuff with boolean ANDs. I don't really want to assume anything, but I don't think you want to be using "&&" like that. Maybe you do, but in either case, it sure makes for hard-to-read code.

Sorry if this doesn't help.


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