Calculating Percent

[hermit22]

Before I begin, I apologize if this is something stupid on my part, or it's a question that's already been answered.

Basically, I need to calculate the percentage of 1 data set to another. So I have this:

int percentage = 0;
DataRow r = dsLocal.Tables[0].Rows[0];
int curr_count = System.Convert.ToInt32(r[0]);
if (curr_count > 0)
  {percentage = (curr_count % total);}
else
  {percentage = 0; }

When I run it, my messagebox output:

MessageBox.Show(percentage.ToString(+" "+curr_count.ToString()+ "/"+total.ToString());

shows that the percentage is only assigned curr_count. So, in the first example, I have:

curr_count = 159
total = 297
percentage = 159

although percentage should equal 53. Any ideas?

 

[obislavu]

The following statement
{percentage = (curr_count % total);}
calcualte the modulo between curr_count and total and never a percentage e.g. which percent is curr_count from the total!
The m%n operation calculates the rest when you divide m by n.
Example: 10 %2 --> 0
23 % 2 --> 1
Generally if m, n are positive integers then m%n is the r number that satisfy the egality:
m = q * n + r
Always : 0<=r< n

In your case : 159% 297 is 159 !
Why ?
159 = 0 * 297 + 159

In order to calculate the right percentage do:
if (total > 0)
percentage = 100* curr_count / total
else ...

-obislavu-

 

[chiph]

Like obislavu says -

The Percent operator (%) is the modulus operator. In order to calculate a percentage you need to divide one by the other, then multiply by 100.

Note that he is doing the multiplication first. This is because he's using integer variables, and if you did the division first you'd get 0 or 1 as a result when the results are truncated to fit the int result variable.

Chip H.


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