type | description |
---|---|
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. |
Each of these three types of loops can be built using the while
and other
statements.
The loops have to be built out of several of the fundamental statements because there
are three things (in each of the three types of loops) that have to be done correctly:
Usually each of these three considerations is located in a different spot. No wonder that loops often go wrong! The flow chart to the left shows what all loops must do. The ellipses (. . . .) shows where the loop can do additional computation in its body. Overlooking one of these three aspects usually results in an incorrect loop and a sometimes difficult to find program bug!