Boolean Expressions in C#

The logical operators let you test more than one expression.

A double ampersand, && means AND. A double pipe or bar || means OR. The pipe is typed using shift + backspace.

Truth table

a b a&&b a||b
false false false


false true false true
true false false true
true true true true

Notice that || (or) is an inclusive or. If the boss says you will get a bonus if you get 10 new customers or sell 100 widgets, then you would get the bonus if you did both.

int newCustomers = 12;
int widgetsSold = 100;
if (newCustomers>=10 || widgetsSold>=100) Text = "You get a bonus";
else Text = "Sorry, you don't get a bonus";

Also, in English we might say "Children and Senior get a discount." However one person can't be both a child and a senior. Reword this for the inidvidual: "You will get a bonus is you are a child or a senior."

 if (age <= 12 || age >= 55) Text = "You get a discount";
 else Text = "Sorry, you don't get a discount";

All of these examples can be tested by starting a new Windows form app and testing in form load without adding any controls.
If you want to really test, you can add a scroll bar to select the values.

NEXT: Drill on Boolean