A First Book of ANSI C—ch05.pptVIP

Linux+ Guide to Linux Certification, Second Edition A First Book of ANSI C, Fourth Edition A First Book of ANSI CFourth Edition Chapter 5 Repetition Objectives Basic Loop Structures The while Statement Computing Sums and Averages Using a while Loop The for Statement Objectives (continued) Case Studies: Loop Programming Techniques Nested Loops The do-while Statement Common Programming and Compiler Errors Introduction A section of code that is repeated is called a loop, because after the last statement in the code is executed, the program branches, or loops, back to the first statement and starts another repetition through the code Each repetition is also called an iteration or pass through the loop Basic Loop Structures Constructing a repeating section of code requires that four elements be present: Repetition statement while statement for statement do-while statement Condition A statement that initially sets the condition being tested A statement within the repeating section of code that alters the condition so that it eventually becomes false Pretest and Posttest Loops Pretest and Posttest Loops (continued) Counter-Controlled and Condition-Controlled Loops Counter-controlled loop: the condition is used to keep track of the number of repetitions Also known as a fixed-count loop Condition-controlled loop: the tested condition does not depend on a count being achieved, but rather on a specific value being encountered Basic Loop Structures The while Statement The general form of the while statement is while (expression) statement; The transfer of control back to the start of a while statement to reevaluate the expression is known as a program loop The following is a valid but infinite loop: while (count = 10) printf(%d ,count); The while Statement (continued) The while Statement (continued) The while Statement (continued) Computing Sums and Averages Using a while Loop Computing Sums and Averages Using a while Loop (continued) Sentinels A program, such