Thread: Desperate !! In need of a helping hand...

oops

could anybody give me like an example program of how they would go about tackling this problem. then i can see what has been done and how it works with my variables. because im finding it difficult to follow all the advice that has been given. cheers

ok so iv been trying loads of combos and i think i got it...

but i cant seem to get the second column of my table right, the values are all wrong. i have checked the maths but cant seem to figure out why. Cheers.

Code:

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

// Define Variables

struct parameters
{
	double max_moment;              
	double min_moment;              
	double no_inc;            
	double inc_diff;          
	double i;
	double depth;
	double breadth;
	double moment_area;
	double moment;
	double stress;
	struct parameters *next;

};

int main(void)
{

// Define struct components

	struct parameters parametersvariable, *parameters_ptr;
	struct parameters *first_ptr, *new_ptr, *previous;
	struct parameters *list_ptr;  
		
	parameters_ptr = &parametersvariable;
    
	{

// Prompt user to input depth, breadth, min_moment, max_moment and no_inc

		fprintf(stdout, "This program will calculate Max/Min Stress over a range of Applied Moments.\n");
		fprintf(stdout, "The Results will be displayed in table-form at the end.\n\nLets Begin...");
		fprintf(stdout, "\n\n1. Enter the value for Depth of the Beam: [m]:  ");
			fscanf(stdin, "%lf", &parameters_ptr->depth);
		fprintf(stdout, "\n\n2. Enter the value for Breadth of the beam [m]:  ");
			fscanf(stdin, "%lf", &parameters_ptr->breadth);
		fprintf(stdout, "\n\n3. Enter the value of the Minimum Applied Moment [Nm]:  ");
			fscanf(stdin, "%lf", &parameters_ptr->min_moment);
		fprintf(stdout, "\n\n4. Enter the value of the Maximum Applied Moment [Nm]:  ");
			fscanf(stdin, "%lf", &parameters_ptr->max_moment);
		fprintf(stdout, "\n\n5. Enter the Number of Increments between the Min and Max Applied Moments:  ");
			fscanf(stdin, "%lf", &parameters_ptr->no_inc);
        
// Calculate the difference between each increment

		parameters_ptr->inc_diff = (parameters_ptr->max_moment-parameters_ptr->min_moment)/parameters_ptr->no_inc;
        parameters_ptr->moment_area  = (parameters_ptr->breadth * (parameters_ptr->depth * parameters_ptr->depth * parameters_ptr->depth)) / 12;

// Work out the values of applied moment using a loop, counter and put in a linked list

		first_ptr = NULL;
		for(parameters_ptr->i=0; parameters_ptr->i<parameters_ptr->no_inc;parameters_ptr->i++)    
		{
			new_ptr = (struct parameters *)malloc(sizeof(struct parameters));
			if (first_ptr != NULL)
				previous->next = new_ptr;
			else
				first_ptr = new_ptr;
			new_ptr->next = NULL;
			
			new_ptr->moment = parameters_ptr->min_moment + (parameters_ptr->i * parameters_ptr->inc_diff);              
			new_ptr->stress = (parameters_ptr->moment * parameters_ptr->depth) / (2 * parameters_ptr->moment_area);
			
			previous = new_ptr;
		}

		fprintf(stdout,"\n\nMoments [Nm]         Max/Min Stress [N/m2]\n");
		list_ptr = first_ptr;
		while(list_ptr != NULL)
		{
			fprintf(stdout, "\n%.2lf      %.2lf\n", list_ptr->moment, list_ptr->stress);
			list_ptr = list_ptr->next;  
		}
		return(0);
	}
}

YAY!

i managed to correct the last part just now... within the while loop (the second equation) was taking a pointer from the wrong moment value. it was nt using the value of moment it had just created. it should have read:

Code:

new_ptr->stress = (new_ptr->moment * parameters_ptr->depth) / (2 * parameters_ptr->moment_area);

where parameters_ptr->moment replaced with new_ptr->moment

id just like to say thanks to salem and jafet who have helped me greatly, i took your advice i created an array to begin with then with that confidence went on to make my own linked list. now all it needs is for me to sex it up a bit. cheers guys