You use a loop to repeat the execution of code statements. A loop is a structure that repeats the execution of code until a condition becomes false.
You learned in this chapter how to use one type of loop: the for loop. However, before discussing the for loop, I showed you how to use increment and decrement operators, which are used in for and other types of loops . I then explained the difference between prefix and postfix when using the increment and decrement operators.
You also learned in this chapter how to use the break keyword to prematurely terminate a for loop and the continue keyword to prematurely terminate the current iteration of the loop. You then learned how to use the logical operators as an alternative to the break and continue keywords. You also learned about nesting one for loop inside another.
The for loop generally is used when the loop will execute a fixed number of times. However, sometimes the number of times a loop will execute is unpredictable, depending on user input during runtime. For example, in a data entry application, you may want a loop that, upon entry of invalid data, asks the user whether they want to retry or quit, and if they want to retry , gives the user another opportunity to enter data. The number of times this loop may execute is unpredictable, since it will keep repeating until the user either enters valid data or quits.
The next chapter will show you how to use two other types of loops, the while loop and the do while loop, that work better than a for loop when the number of times a loop will execute is unpredictable.