C# SUM multiply calculation over fields

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2.00/5 (1 vote)

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I would like to calculate a selling price based on field 1 (the purchase price) and field2 (storage in pergentages). What am I doing wrong with the formula below.

Simple sum field1 = 1.00 x 30 field two (30%) = field3

C#

<pre>
int a, b;

bool isAValid = int.TryParse(XX_ field1.Text, out a);
bool isBValid = int.TryParse(XX_ field2.Text, out b);

                            if (isAValid && isBValid)
                            {
                                LB_verkoopprijs.Text = (a * b).ToString();
                            }

                            else
                            {
                                LB_verkoopprijs.Text = "Invalid input";
                            }

Posted 28-Dec-15 2:44am

MaikelO1

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OriginalGriff · Accepted Answer · 2015-12-28T03:00:00

Two possibilities:
1) The spaces in your source code are preventing it compiling properly:

C#

bool isAValid = int.TryParse(XX_ field1.Text, out a);
bool isBValid = int.TryParse(XX_ field2.Text, out b);

Should probably be:

C#

bool isAValid = int.TryParse(XX_field1.Text, out a);
bool isBValid = int.TryParse(XX_field2.Text, out b);

Or
2) The textboxes don't contain integer numbers.
Your example suggests that you are entering "1.00" as "field1" which will not parse as an integer.
Try:

C#

double a, b;
 
bool isAValid = double.TryParse(XX_ field1.Text, out a);
bool isBValid = double.TryParse(XX_ field2.Text, out b);

And you might get something better.

But to get 30% of something, you don't want "a * b": you need "a * (b / 100.0)" for 30% of the purchase price, or "a * (1.0 + b / 100.0)" for the purchase price plus 30%