How to use an integer as a percentage in C# (Without using doubles)

Question

How do I use an int variable as a percentage, to calculate data. For example, I'm doing a practice for "Passing Arguments" in C# and I need to read in two integers, a salary and a raise. For example 5000 & 15. Im supposed to figured out the total salary after 5000 has been increased by 15%
Here's my code but I don't understand why the math is correct on paper, yet not in the computer.

static void Main(string[] args)
{
int salaryBudget = Convert.ToInt32(Console.ReadLine());
int percent = Convert.ToInt32(Console.ReadLine());

Console.WriteLine("Before the increase: " + salaryBudget);

//complete the method call
Increase(ref salaryBudget, ref percent);

Console.WriteLine("After the increase: " + salaryBudget);
}
//complete the method
static void Increase(ref int a, ref int b)
{
a = (a + (a * (b/100)))
}

Answer 1

Because `b / 100` (which yields 0) is wrapped in parentheses, it is calculated first before it is multiplied by <a>.

So
( a * ( b / 100 ) ) is evaluated as
( a * ( 0 ) ) because integer division reserves no fraction part.

And it wraps up into
a = ( a + ( a * ( 0 ) ) ) which equals
a = ( a + ( 0 ) )

And there's the reason. Remove the parentheses around b / 100 and it'll be fine.

a = ( a + ( a * b / 100 ) ); // <- like this

P.S. I don't think <b> needs to be passed by reference, it is not being modified in the `Increase` function.

Answer 2

Ipang much appreciation!