The For Statement

The 'for' loop is more compact than the 'while' and 'do' loops and automatically updates the loop counter at the end of each iteration. Both 'for' and 'while' loops are designed for different situations. You'll learn more about when to use each later.

2. Fundamental Loops


counting loop

Uses a loop control variable to count upwards or downwards (usually by an integer increment.)

sentinel-controlled loop

Loop keeps going until a special value is encountered in the data.

result-controlled loop

Loop keeps going until a test determines that the desired result has been achieved.

Fundamental Loops

loopChart Each type of loop can be built using the while along with other statements. There are three things (in every type of loop) that must be done correctly:

  1. The loop must be initialized.
  2. A condition must be tested.
  3. The loop body must change something that is tested.

Overlooking one of these aspects results in a defective loop. But usually each of these aspects is found in a different place in a program. No wonder that loops often go wrong!

The flow chart to the right shows what all loops must do. It could be for any of the three types of loops. The ellipses (. . . .) shows where the loop body does additional computation.

Question 2:

Would it be convenient to have all three aspects combined into one statement?