Introduction to Loops

Repetition

The repetition of an instruction or a group of instructions is a commonly encountered phenomenon in programming. It is called a loop. As an example, say we want our program to perform the following tasks:

• To read a document or data file line by line repeatedly until the end of the file.
• To draw an image pixel by pixel repeatedly using color values that show it on the screen.
• To iterate through a collection of variables one by one to process its values.
• To compute a result by applying a formula to several values.