Thread: Optimise?

Hi there, newbie to the forum but long time C-programmer, although not 100% up to it. Haha!!! I program primarily to do data manipulation, stuff that can really be done in MathCAD or excel, but lacks the cool factor. Tend to work with large arrays of numbers. Hence, I've typically been using arrays most of the time.

Recently, my new job has moved me to a windows platform, and I've downloaded the lcc-win32 compiler. Now, when my arrays are smallish, the program runs fine... but if I bring it up to say a[10000], it blows up - program doesnt run.

Can anyone provide a hindsight on how I can optimize the program... or maybe how to increase allocated memory?

Snippets of my code is below: (Yes, I do need that many variables!!)

Its all set at [100] which runs, but if I increase to [10000] (which I need now!), it doesnt!

Thanks in advance!!!

Thom

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void title(void);

int main(int argv, char *argc[])
{
	int i=0, j=0, ch=0;
    int count=1;
	float kp[100], ethermal[100], nt[100], e_sp1[100], e_sp2[100], e_sp3[100], e_sp4[100], fy[100];
	float Pe, d_t, f2, sigma_hoop, EcO, EcI[100], gfunct, Pyc[100], PE1, PE, PC1[100], PC[100];
	float e_sp1_net[100], e_sp2_net[100], e_sp3_net[100], e_sp4_net[100], e_average_net[100];
	float e_bend1_net[100], e_bend2_net[100], e_bend3_net[100], e_bend4_net[100];
	float e_res1[100], e_resultant[100], UR1[100], UR2[100], UR3[100], UR[100];
	float params[16];

	float grav, wd, T_amb, rho_sea, D, WT, CRA, SMYS, SMTS, E, nu, Pi, fluid, f0;

	FILE *fp;
	FILE *fp2;

/* Usage Error trapping */

    if(argv !=3)
    	{
			title();
			printf("ERROR!!! - Proper usage is:\n");
			printf("\n %s input_filename output_filename\n", argc[0]);
			printf("... where input_filename = File to be post-processed\n");
			printf("     and output_filename = File for program output\n");
			return(1);
		}

/* Data Checking */

	if ((fp=fopen(argc[1], "r")) == NULL )
		{
			title();
			printf("Error in Opening File: %s \n\n File is Empty\n\n", argc[1]);
			exit(1);
		}

	while( (ch=fgetc(fp)) != EOF)
	{
		if(ch == '\n')
			count++;
	}

/* Input Files */

	fp=fopen(argc[1],"r");
		for(i=1; i<=count; i++)
			fscanf(fp,"%f %f %f %f %f %f %f\n", &kp[i], &ethermal[i], &nt[i], &e_sp1[i], &e_sp2[i], &e_sp3[i], &e_sp4[i] );

	fclose(fp);

	fp2=fopen("input_params.dat","r");
		for(j=1; j<=15; j++)
			fscanf(fp2, "%f\n", &params[j]);
	fclose(fp2);

/* Variables Definition */

-
-
-
-
-

for(i=1; i<=count; i++)
{
fprintf(fp2,"%.2f,%.2f,%.2f,%.4e,%.4e,%.4e,%.4e,",kp[i],ethermal[i],nt[i],e_sp1[i],e_sp2[i],e_sp3[i],e_sp4[i]);
fprintf(fp2,"%.4e,%.4e,%.4e,%.4e,%.4e,%.4e,%.4e\n",e_bend1_net[i],e_bend2_net[i],e_bend3_net[i],e_bend4_net[i],e_average_net[i],e_resultant[i],UR[i]);
}
fclose(fp2);

	printf("\n\n === The output file %s has been written...program EXITING === \n\n", argc[2]);

	return 0;
}

Thanks vart, but sorry, no experience in malloc.
Does it mean I cant use arrays and need to recast in pointers? (which btw, I'm hopeless in!)

hes got it right dwks

Code:

int main(int argv, char *argc[])

argc is the array

can call them anything really

Wow! Thanks guys! Will try the static approach first (completely forgot about that!!!)...
vart, what does that piece of code do? I dont have my compiler with me now to try!

dws, errr.... been using that approach for years without complains!

Originally Posted by vart

Are you sure, that you are "long time C-programmer"?

This piece of code shows how to use dynamically allocated array of 100 doubles.

the code inside if block has no difference from the usage of the static array... That what I tried to illustrate with this sample

Yes I know... hence the smiley. I've heard horror stories from friends of how some aggressive people live and thrive on this board, and was just testing water!

Cool down guys! Peace!

Originally Posted by Prelude

>dws, errr.... been using that approach for years without complains!
Yes, but how many people have had to maintain your code? I can understand using other names, like count and list, or ac and av, but swapping argc and argv just seems too much like you're screwing with us.

Nobody!!
And I do have a bad habit of messing variable names up where they shouldnt be.. sorry!