assigning coordinates to triangles

[sanehatter]

Hi,

I am trying to write a simple program that assigns x,y coordinates to the centroids and angles of trianlges. This is the code:




# include <iostream>
#include <fstream>

using namespace std;

float rightisosceles [100][4][10];
float n, n1;
float ydisplacement2 = 0.0;
float righttrianglebase = 1.0;
float righttriangleheight = 1.2;
int v = 1, isoscelescounter = 1;
int p, hh, oo, pp;


int main()

{


for (hh = 0; hh <=100; hh++) {
for (oo = 0; oo <=100; oo++) { for (pp = 0; pp <=100; pp++)
{
rightisosceles [hh][oo][pp] = 0.0;


}
}
}

{


for (n = 3.0 ; n <= 70; n + 5) {
for (n1 = 4.0 ; n1 <= 39; n1 + 5 ) {

rightisosceles [v][0][0] = n1 ; // right isosceles x coordinates
rightisosceles [v][1][0] = (rightisosceles [v][0][0]) + (righttrianglebase /2);
rightisosceles [v][2][0] = (rightisosceles [v][0][0]) - (righttrianglebase /2);
rightisosceles [v][3][0] = (rightisosceles [v][0][0]);

rightisosceles [v][0][1] = n ; // right isosceles y coordinates
rightisosceles [v][1][1] = (rightisosceles [v][0][1]) + (righttriangleheight /3);
rightisosceles [v][2][1] = (rightisosceles [v][1][1]);
rightisosceles [v][3][1] = (rightisosceles [v][2][1]) - (righttriangleheight);

v = v + 1;
isoscelescounter = isoscelescounter + 1;

cout << rightisosceles [v][0][0] << endl;
}
}

}
}



When I run the program, a console window opens with nothing in it and I dont get any results. I am not sure why.Can anyone help with this.

Thanks.

[hamsterman]

Maybe the program crashes when the first 3 for loops write out of bounds of rightisosceles. The sizes are [100][4][10] but you write form 0 to 100 in each place. Note that from 0 to 100 there are 101 values while you only have 100 so even the first loop isn't right. You should use < in your for loops.

Another problem is with your other for loops. n+5 does not modify n, so the loop would be infinite. The right way would be n=n+5 or n+=5.

[sanehatter]

Thank you hamsterman. I modified the code but it is still having a problem... it's giving me all 0s for the values with the exception of 2 values and then it crashes and the operating system shuts it down. I am using code::blocks with Win XP. Here is the modified code:




# include <iostream>
#include <fstream>

using namespace std;

float rightisosceles [100][4][10];
float n, n1;
float ydisplacement2 = 0.0;
float righttrianglebase = 1.0;
float righttriangleheight = 1.2;
int v = 1, isoscelescounter = 1;
int p, hh, oo, pp;


int main()

{


for (hh = 0; hh <100; hh++) {
for (oo = 0; oo <4; oo++) { for (pp = 0; pp <10; pp++)
{
rightisosceles [hh][oo][pp] = 0.0;


}
}
}



for (n = 3.0 ; n <=70; n = n + 5) { // positioning particles
for (n1 = 4.0 ; n1 <= 39; n1 = n1 + 5) {



rightisosceles [v][0][0] = n1 ; // right isosceles x coordinates
rightisosceles [v][1][0] = (rightisosceles [v][0][0]) + (righttrianglebase /2);
rightisosceles [v][2][0] = (rightisosceles [v][0][0]) - (righttrianglebase /2);
rightisosceles [v][3][0] = (rightisosceles [v][0][0]);

rightisosceles [v][0][1] = n ; // right isosceles y coordinates
rightisosceles [v][1][1] = (rightisosceles [v][0][1]) + (righttriangleheight /3);
rightisosceles [v][2][1] = (rightisosceles [v][1][1]);
rightisosceles [v][3][1] = (rightisosceles [v][2][1]) - (righttriangleheight);

v = v + 1;
isoscelescounter = isoscelescounter + 1;

cout << rightisosceles [v][0][0] << endl;
}
}

}

[hamsterman]

The same. You never make sure that v < 100. If it is not, the program crashes.

[sanehatter]

ok. I increased the size of rightisosceles [150][4][10]. The program is not crashing anymore but the x,y values are all 0s. This is the modified program:



# include <iostream>
#include <fstream>

using namespace std;

float rightisosceles [150][4][10];
float n, n1;
float ydisplacement2 = 0.0;
float righttrianglebase = 1.0;
float righttriangleheight = 1.2;
int v = 1, isoscelescounter = 1;
int p, hh, oo, pp;


int main()

{


for (hh = 0; hh <150; hh++) {
for (oo = 0; oo <4; oo++) { for (pp = 0; pp <10; pp++)
{
rightisosceles [hh][oo][pp] = 0.0;


}
}
}



for (n = 3.0 ; n <=70; n = n + 5) { // positioning particles
for (n1 = 4.0 ; n1 <= 39; n1 = n1 + 5) {



rightisosceles [v][0][0] = n1 ; // right isosceles x coordinates
rightisosceles [v][1][0] = (rightisosceles [v][0][0]) + (righttrianglebase /2);
rightisosceles [v][2][0] = (rightisosceles [v][0][0]) - (righttrianglebase /2);
rightisosceles [v][3][0] = (rightisosceles [v][0][0]);

rightisosceles [v][0][1] = n ; // right isosceles y coordinates
rightisosceles [v][1][1] = (rightisosceles [v][0][1]) + (righttriangleheight /3);
rightisosceles [v][2][1] = (rightisosceles [v][1][1]);
rightisosceles [v][3][1] = (rightisosceles [v][2][1]) - (righttriangleheight);

v = v + 1;
isoscelescounter = isoscelescounter + 1;

cout << rightisosceles [v][0][1] << endl;
cout << rightisosceles [v][1][1] << endl;
cout << rightisosceles [v][2][1] << endl;
cout << rightisosceles [v][3][1] << endl;

}
}

}



Why is the second loop not functioning correctly? It is supposed to give me values other than 0s.

[hamsterman]

You increment v before printing, so the value you print is not the value you just computed.

[sanehatter]

Thank you hamsterman but again all values I have are 0s. I tried printing the n's n1's and v's and they print just fine but when I try to assign values to the array (any array) they keep on giving me 0s.Something is not working in this code, or could it be a software glitch..because it totally does not make any sense.

[hamsterman]

Did you misunderstand my last post? Look, let's take the first cycle, where v = 0.
First you set rightisosceles [0][0][1] to n and etc.
Then you increment v so that it is 1.
And finally you print rightisosceles [1][0][1]. You filled all the array with 0s, so of course, the next element will be 0.
Now if you do incrementing after printing, this problem will not occur.

[sanehatter]

You are absolutely right..thank you so much...