Thread: Issue with function calls

Hello! I'm working on an assignment question as follows:
Screenshot by Lightshot

I've written the following code:

Code:

/*    File: lumberfunc.c
    This file reads base and height from an input file then uses 3 function to compute the values of the required engineering properties.
*/

#include<stdio.h>

float area(int base,int height) 
{
    float result;
    
    result = base*height;
    
    return result;
}

float mod(int height)
{
    float area,result;
    
    result = (area*height)/6.0;
    
    return result;
}

float inertia(int height)
{
    float mod,result;
    
    result = (mod*height)/2.0;
    
    return result;
}

int main(void)
{
    int base, height;
    float csarea, moinertia, secmod;
    
    FILE * fin = fopen("lumberin.txt","r");
    FILE * fout = fopen("lumberout.txt","w");
    
    fprintf(fout,"Lumber Size      Cross sectional      Moment of      Section\n                     Area             Inertia        Modulus\n--------------------------------------------------------------\n");
    
    while(fscanf(fin,"%d %d\n",&base,&height) != EOF) {
        
        csarea=area(base,height);
        
        secmod=mod(height);
        
        moinertia=inertia(height);
        
        fprintf(fout," %d x  %d             %.2f              %.2f           %.2f\n",base,height,csarea,moinertia,secmod);
    }
    
    fclose(fout);
    
    return 0;
}

My output is as follows:
Screenshot by Lightshot

Now, formatting issues aside, my Moment of Inertia isn't calculating correctly. In the inertia() function, for some reason mod = area, even though in main, secmod = mod is returning the correct value. Could someone explain to me what's going wrong here and how to fix it?

Thank you for your time!

Unfortunately the assignment specifically wants inertia() to call modulus().

I replaced the modulus and area variables with proper function calls and it works now:

Code:

/*    File: lumberfunc.c
    This file reads base and height from an input file then uses 3 function to compute the values of the required engineering properties.
    
    Programmer: Sara Stredulinsky    Date: 15-Oct-19
*/

#include<stdio.h>

/*Prototypes*/
float area(int base,int height);
float modulus(int base, int height);
float inertia(int base, int height);

int main(void)
{
    int base, height;
    float csarea, moinertia, secmod;
    
    FILE * fin = fopen("lumberin.txt","r");
    FILE * fout = fopen("lumberout.txt","w");
    
    fprintf(fout,"Lumber Size      Cross sectional      Moment of      Section\n                     Area             Inertia        Modulus\n--------------------------------------------------------------\n");
    
    while(fscanf(fin,"%d %d\n",&base,&height) != EOF) {
        
        csarea=area(base,height);
        
        secmod=modulus(base,height);
        
        moinertia=inertia(base,height);
        
        fprintf(fout," %d x  %d             %.2f              %.2f           %.2f\n",base,height,csarea,moinertia,secmod);
    }
    
    fclose(fout);
    
    return 0;
}

float area(int base,int height) 
{
    float result;
    
    result = base*height;
    
    return result;
}

float modulus(int base,int height)
{
    float result;
    
    result = (area(base,height)*height)/6.0;
    
    return result;
}

float inertia(int base, int height)
{
    float result;
    
    result = (modulus(base,height)*height)/2.0;
    
    return result;
}

But I still don't get why in the original code modulus() correctly calls area() and uses ((base*height)*height)/6.0 as its calculation, but inertia() which looks like it's built identically to me, calls area() again for ((base*height)*height)/2.0 instead of calling modulus to make (((base*height)*height))/2.0. Can anyone explain what was happening there?

Originally Posted by LioButtons

But I still don't get why in the original code modulus() correctly calls area() and uses ((base*height)*height)/6.0 as its calculation, but inertia() which looks like it's built identically to me, calls area() again for ((base*height)*height)/2.0 instead of calling modulus to make (((base*height)*height))/2.0. Can anyone explain what was happening there?

In your original code

Code:

float mod(int height)
{
    float area,result;
     
    result = (area*height)/6.0;
     
    return result;
}

What is the value of 'area'?