# 5.1. Conditions I¶

Thus far, within a given function, instructions have been executed sequentially, in the same order as written. Of course that is often appropriate! On the other hands if you are planning your instruction sequence, you can get to a place where you say, “Hm, that depends....”, and a choice must be made. The simplest choices are two-way: do one thing if a condition is true, and another (possibly nothing) if the condition is not true.

More syntax for conditions will be introduced later, but for now consider simple arithmetic comparisons that directly translate from math into C#. First start csharp an enter:

int x = 11;


Now think of which of these expressions below are true and which false, and then enter each one into your csharp session to test:

2 < 5
3 > 7
x > 10
2*x < x


You see the C# values, either true or false (with no quotes!). These are the only possible Boolean values (named after 19th century mathematician George Boole). You can also use the abbreviation for the type bool. It is the type of the results of true-false conditions or tests.

The simplest place to use conditions is in a decision made with an if statement.

We will consider More Conditional Expressions later, but this is a quick start with the easiest ones.