Need Help with a code

Ok...here's the deal. I am struggling on a code and its part of my homework so i was gonna post it into the homework section, but then I feel that i wouldn't have a great deal of response. So, maybe i could get a better response here. Its basic C programming.

I kind of understand the problem. I know their is a if, else...but the problem I am having is trying to get to do what I want. Here, I'll show a simple version of what I have so far...

Thats all I have so far. Its not complete yet. I know that I have to brute force the if/else area but i have trouble trying to do the function. Can anyone help?

 

any ideas anyone? I need to get this code done before Tuesday. So, please help me.

 

http://www.cprogramming.com/tutorial/c/lesson4.html

 

I understand how to write functions. I just don't know what to do with all the reference numbers running through the equations

 

Ok, first of all, the function definition should be:

Code (Text):

1. bool within_x_percent(int ref, int data, double x)

Then the function would be:

Code (Text):

1. if( (ref - x*ref)<= data || data <= (ref + x*ref) )
2. return true;
3. else
4. return false;

 

It may be late but here a full solution.

Code (Text):

1. #include <stdio.h>
2.  
3. /* Prototype */
4. bool within_x_percent(double SubtanceA, double SubtancesB, double percentage);
5.  
6.  
7. // Constants
8. const double Water = 100.0;
9. const double Mercury = 357.0;
10. const double Copper = 1187.0;
11. const double Silver = 2193.0;
12. const double Gold = 2660.0;
13.  
14.  
15. int main()
16. {
17.     /* declared variables */
18.     double subtanceA=0,percentage =0;
19.         int subtanceB=0.0;
20.     /* Prompt the user */
21.     //we get the subtanece
22.     printf("Enter subtance  : ");  
23.     scanf("%d", &subtanceB);
24.     //here the tolerance
25.     printf("Enter percentage : ");
26.     scanf("%d", &percentage);
27.  
28.     //here an example how to use it
29.     if(within_x_percent(Water,subtanceB,10 ))
30.         printf("the subtance is water ! : ");
31.  
32.     return 0;
33. }
34.  
35. bool within_x_percent(double SubtanceA, double SubtancesB, double percentage)
36. {
37.     double range = SubtanceA  * (percentage/100) ;
38.     double topRange = SubtanceA + range ;
39.     double bottomRange = SubtanceA  - range ;
40.     if(SubtancesB >= bottomRange && SubtancesB <= topRange )
41.     {
42.         return true;
43.     }
44.     else
45.         return false;
46. }