Online Learning Tuts: while

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<span style="font-family: "verdana" , sans-serif; font-size: 16pt; line-height: 107%; text-align: justify;">The </span><span style="font-family: "consolas"; font-size: 16pt; line-height: 107%; text-align: justify;">for</span><span style="font-family: "verdana" , sans-serif; font-size: 16pt; line-height: 107%; text-align: justify;">
loop does something we know in advance that how many times a loop has to be
executed.</span></div>
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<span style="font-family: "verdana" , sans-serif; font-size: 16.0pt; line-height: 107%;">But if you don’t know that
how many times your loop is going to be run then </span><span style="font-family: "consolas"; font-size: 16.0pt; line-height: 107%;">while</span><span style="font-family: "verdana" , sans-serif; font-size: 16.0pt; line-height: 107%;">
loop is the choice.<o:p></o:p></span></div>
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<b><span style="font-family: "verdana" , sans-serif; font-size: 22.0pt; line-height: 107%;">Syntax<o:p></o:p></span></b></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">While(condition)<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">{<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">     Statement(s);<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">}<o:p></o:p></span></div>
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<span style="font-family: "verdana" , sans-serif; font-size: 16.0pt; line-height: 107%;">The flow diagram for it is:<o:p></o:p></span></div>
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<span style="font-family: "verdana" , sans-serif; font-size: 16.0pt; line-height: 107%;">Let’s have a look at an
example:<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">#include <iostream> <o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">using namespace std;<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">int main(){<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">int n = 99;     // make sure n isn’t initialized to 0<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">while( n != 0 )   // loop until n is 0 <o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">cin >> n;      // read a number into n <o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">cout << endl;<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">return 0;<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">}<o:p></o:p></span></div>
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<span style="font-family: "verdana" , sans-serif; font-size: 16.0pt; line-height: 107%;">Here’s some sample output.
The user enters numbers, and the loop continues until 0 is entered, at which
point the loop ends and the program is terminated.</span><span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;"><o:p></o:p></span></div>
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<b><span style="font-family: "consolas"; font-size: 18.0pt; line-height: 107%;">Output:<o:p></o:p></span></b></div>
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<span style="font-family: "consolas"; font-size: 16.0pt; line-height: 107%;">1 27 33 144 9 0<o:p></o:p></span></div>
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<b><span style="font-family: "verdana" , sans-serif; font-size: 24.0pt; line-height: 107%;">                  <o:p></o:p></span></b></div>
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<span style="font-size: 20.0pt; line-height: 107%;"><o:p></o:p></span></div>

The while loop - loops - repetition - control structures

The for loop does something we know in advance that how many times a loop has to be executed. But if you don’t know that how many times ...