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Control Structures

Most programming languages use 3 basic control structures:

• Sequence: statements are executed one after the other.
• Selection or branching: One statement or group of statements is executed if a Boolean expression is true, another (optional) statement or group of statements is executed if the Boolean expression is false.
• Iteration or looping: One statement or group of statements is executed repeatedly until some exit condition is met.

In programming languages where there is a graphical user interface (GUI) the program will repeatedly "listen" for events to occur. When an event occurs a function is executed in response to that event. Events include things such as a file finishes loading, the user clicks a button, moves the mouse or types a key.

These types of programs are called event driven programs.