Creating and writing to large arrays

[abunn]

I've been learning Visual C++ on the fly at work for the last 2 weeks and could use some help. I'm writing a program to read a .raw file which has a standard format of 9 columns and then depending on the size of the object, a large number of rows. I then need to rotate it and write the new position of the object to a new .raw file. I started with a box as a simple example that had only 28 rows. The code worked fine for the small number of rows, but the objects I'll be using have approx. 35000 rows and it's overloading the arrays "geom" and "geom_r". Any tips for me to get around this would be greatly appreciated.
Thanks,
Adam Bunn

#include<iostream.h> //For input/output
#include<math.h>  //For math functions
#include<stdio.h> //For fopen, FILE...
int main()
 
{
    //Declaration of Variables
    const float pi = 3.14159f;
    float degrees = 45.0f;
    float radians  = degrees * pi / 180;
    int i, j, k, p, q, r, s, c, d, w, lines;
    float geom[28][9];
    float geom_r[28][9];
    float vertice1[3][1], vertice2[3][1], vertice3[3][1];
    float r_vertice1[3][1], r_vertice2[3][1], r_vertice3[3][1];
    float sum1, sum2, sum3;
    float z_rotate[3][3] = {
                                {cos(radians), -sin(radians), 0},    //rotation matrices
                                {sin(radians), cos(radians), 0},
                                {0,0,1}
                            };
    float y_rotate[3][3] = {
                                {cos(radians), 0, -sin(radians)},
                                {0,1,0},
                                {sin(radians), 0, cos(radians)}
                            };
 
    FILE * praw;  //Open file to read
    praw = fopen("D:\\Adam\\Hip ROM Project\\C++\\figure_it_out\\box.raw", "r");  //File name!
 
    //for (i = 0; i < 28; i++){ //Read file into box array
    i = 0;
    while (!feof(praw)) {
        for (j = 0; j < 9; j++){
            fscanf(praw, "%f", &geom[i][j]);
        }
        i = i +1;
    }
    fclose(praw);
 
    lines = i - 1;  //number of lines in the file
    for (p = 0; p < lines; p++){  //Break the rows of the array into 3x1 vectors
        r = 3; s = 6; //initialize counters
        for (q = 0; q < 3; q++){
            vertice1[q][0] = geom[p][q];   //First three columns into first vertice
            vertice2[q][0] = geom[p][r];   //Second three columns into second vertice
            vertice3[q][0] = geom[p][s];   //Third three columns into third vertice
            r = r + 1;    //increase counters
            s = s + 1;       
 
        }
 
 
        for(i=0;i<3;i++){ //Multiply matrices to rotate geometry
            j = 0;
            sum1 = 0; sum2 = 0; sum3 = 0;
            for(k=0;k<3;k++){
                sum1 = sum1 + (y_rotate[i][k] * vertice1[k][j]);
                sum2 = sum2 + (y_rotate[i][k] * vertice2[k][j]);
                sum3 = sum3 + (y_rotate[i][k] * vertice3[k][j]);
                r_vertice1[i][j] = sum1;
                r_vertice2[i][j] = sum2;
                r_vertice3[i][j] = sum3;
            }
 
        }
        for (w = 0; w < 3; w++){  //Store rotated vertices in new array, box_r
            c = w +3; d = w + 6;
            geom_r[p][w] = r_vertice1[w][0];
            geom_r[p][c] = r_vertice2[w][0];
            geom_r[p][d] = r_vertice3[w][0];
        }
    }
 
    praw = fopen("D:\\Adam\\Hip ROM Project\\C++\\figure_it_out\\box_r.raw", "a"); //Write new array to new file by appending
    for (i = 0; i < lines; i++){
        for (j = 0; j < 9; j++){
            fprintf(praw, "%f ", geom_r[i][j]);
        }
        fprintf (praw, "\n");
    }
    return 0;
}
 

[Savage]

I've been learning Visual C++ on the fly at work for the last 2 weeks and could use some help. I'm writing a program to read a .raw file which has a standard format of 9 columns and then depending on the size of the object, a large number of rows. I then need to rotate it and write the new position of the object to a new .raw file. I started with a box as a simple example that had only 28 rows. The code worked fine for the small number of rows, but the objects I'll be using have approx. 35000 rows and it's overloading the arrays "geom" and "geom_r". Any tips for me to get around this would be greatly appreciated.
Thanks,
Adam Bunn

Do you know how to allocate dynamic memory?

Savage

[abunn]

I'm trying to wrap my head around it, as well as the use of pointers in general, but the book I've got doesn't give a good example of how to do things multi dimensionally.

[Savage]

I'm trying to wrap my head around it, as well as the use of pointers in general, but the book I've got doesn't give a good example of how to do things multi dimensionally.

When allocating multidimensional arrays on heap,you must first allocate array of pointers,and the for every pointer you allocate array of data that pointer can point to.In your float example that would be:

float **somefloat;
 
somefloat=new float*[elements in 1D];
for(i=0;i<1D;i++) somefloat[i]=new float[elements in 2D];

But when you are done with it you must free it using reverse process.

Savage

[Savage]

Other solution is to use STL's vectors,if you know how to use them,which manages its memory all by it self.


Savage

[abunn]

Thanks for the help. I was able to get that to work pretty easily. There is one other thing that you might be able to help me with. Is there a way to determine how many lines/rows the .raw file has before I set how much memory is dynamically allocated? Or should I just set the array row size high enough that I won't have to worry about a file approaching the max size? If you could point me in the right direction I'd be very greatful. I changed my code to read like this now:

float z_rotate[3][3] = {
                                {cos(radians), -sin(radians), 0},    //rotation matrices
                                {sin(radians), cos(radians), 0},
                                {0,0,1}
                            };
    float y_rotate[3][3] = {
                                {cos(radians), 0, -sin(radians)},
                                {0,1,0},
                                {sin(radians), 0, cos(radians)}
                            };
 
    geom = new float*[40000]; //Dynamic memory allocation
    for (i = 0; i<40000; i++) geom[i] = new float[9];
    geom_r = new float*[40000];
    for (i = 0; i<40000; i++) geom_r[i] = new float[9];
 
    FILE * praw;  //Open file to read
 

Everything else is the same until I delete the arrays near the end. Thanks again

[Savage]

Thanks for the help. I was able to get that to work pretty easily. There is one other thing that you might be able to help me with. Is there a way to determine how many lines/rows the .raw file has before I set how much memory is dynamically allocated? Or should I just set the array row size high enough that I won't have to worry about a file approaching the max size? If you could point me in the right direction I'd be very greatful. I changed my code to read like this now:

float z_rotate[3][3] = {
                                {cos(radians), -sin(radians), 0},    //rotation matrices
                                {sin(radians), cos(radians), 0},
                                {0,0,1}
                            };
    float y_rotate[3][3] = {
                                {cos(radians), 0, -sin(radians)},
                                {0,1,0},
                                {sin(radians), 0, cos(radians)}
                            };
 
    geom = new float*[40000]; //Dynamic memory allocation
    for (i = 0; i<40000; i++) geom[i] = new float[9];
    geom_r = new float*[40000];
    for (i = 0; i<40000; i++) geom_r[i] = new float[9];
 
    FILE * praw;  //Open file to read
 

Everything else is the same until I delete the arrays near the end. Thanks again

Yes,there are varous ways to do that.One is to get size of file and size of single line(there are 9 columns so each row must have same size),and other is a simple while loop,while EOF is not reached read in a line and increase number of lines counter

Savage

[abunn]

Thanks for your help. I got it wrapped up.