PASCAL: AN INTRODUCTION

THE WHILE LOOP
The while loop is similar to the for loop shown earlier, in that it allows a {group of} program statement(s) to be executed a number of times. The structure of the while statement is,

	while   condition_is_true  do
	begin
	        program statement;
	        program statement
	end;         {semi-colon depends upon next keyword}

or, if only a single program statement is to be executed,

	while   condition_is_true   do   program statement;

The program statement(s) are executed when the condition evaluates as true. Somewhere inside the loop the value of the variable which is controlling the loop (ie, being tested in the condition) must change so that the loop can finally exit.

SELF TEST
Determine the output of the following program


	program WHILE_DEMO (output);
	const   PI = 3.14;
	var     XL, Frequency, Inductance : real
	begin
	        Inductance := 1.0;
	        Frequency  := 100.00;
	        while  Frequency < 1000.00 do
	        begin
	            XL := 2 * PI * Frequency * Inductance;
	            writeln('XL at ',Frequency:4:0,' hertz = ', XL:8:2 );
	            Frequency := Frequency + 100.00
	        end
	 end.

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