Online Learning Tuts: Software

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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 ...

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<span style="font-size: 16pt; text-align: justify;">The for loop is the easiest loop in C++ to understand. All elements
of this loop are in one place contrary to those remaining two (while, do-while)
whose elements are scattered in the program.</span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">For loop executes a section of for a certain number of times.<o:p></o:p></span></div>
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<b><span style="font-size: 24.0pt; 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%;">for(initialization; condition; increment)<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%;"> Statements(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-size: 16.0pt; line-height: 107%;">How this
loop works is explained below:<o:p></o:p></span></div>
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<b><span style="font-size: 16.0pt; line-height: 107%;">Initialization: </span></b><span style="font-size: 16.0pt; line-height: 107%;">This is the very first part of for
loop, here you can initialize the counter variable (variable of loop) e.g. i=1
or i=0. But this part is executed only once. This is to initialize the loop.<o:p></o:p></span></div>
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<b><span style="font-size: 16.0pt; line-height: 107%;">Condition:</span></b><span style="font-size: 16.0pt; line-height: 107%;"> This the second part of for loop and
the most important part, this part decides how many times the loop has to be
executed.<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">If the condition is true the loop’s body is executed else it
jumps to next statements.<o:p></o:p></span></div>
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<b><span style="font-size: 16.0pt; line-height: 107%;">Increment:</span></b><span style="font-size: 16.0pt; line-height: 107%;"> if the condition is true there is an
increment in the counter variable. The increment is done using increment
operator “ ++ ”.<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">You can increment in different ways for example:<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">                    <o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">i++      //post
increment<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">++i     //pre increment<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">1+i<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">i+1<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">You can also increment for two or three times, it’s up to you that how many times you want, you
can do this too<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">                          i+3
or i+4<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">After the increment the condition is evaluated again leaving
the first pat this time, if the condition is true the loop executes further
else it is terminated and jumps to the next statements<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">        Here is flow diagram of control<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;"><o:p></o:p></span></div>
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<span style="font-size: 20.0pt; line-height: 107%;">Example:<o:p></o:p></span></div>
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<span style="color: #bc7a00; font-family: "consolas"; font-size: 11.5pt;">#include
<iostream></span><b><span style="color: green; font-family: "consolas"; font-size: 11.5pt;"><o:p></o:p></span></b></div>
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<b><span style="color: green; font-family: "consolas"; font-size: 11.5pt;">using</span></b><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> </span><b><span style="color: green; font-family: "consolas"; font-size: 11.5pt;">namespace</span></b><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> std;<o:p></o:p></span></div>
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<span style="color: #b00040; font-family: "consolas"; font-size: 11.5pt;">int</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> </span><span style="color: blue; font-family: "consolas"; font-size: 11.5pt;">main</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">(){<o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">    </span><span style="color: #b00040; font-family: "consolas"; font-size: 11.5pt;">int</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> x;<o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">    <o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">    </span><b><span style="color: green; font-family: "consolas"; font-size: 11.5pt;">for</span></b><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">(i=0;i<=10;i++) </span><span style="color: #00b0f0; font-family: "consolas"; font-size: 11.5pt;">//the for loop, loop
continues for 10 times</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"><o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">    {<o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">cout </span><span style="color: #666666; font-family: "consolas"; font-size: 11.5pt;"><<</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> </span><span style="color: #ba2121; font-family: "consolas"; font-size: 11.5pt;">“The squre is”</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> </span><span style="color: #666666; font-family: "consolas"; font-size: 11.5pt;"><< i*i <<</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> endl; </span><span style="color: #00b0f0; font-family: "consolas"; font-size: 11.5pt;">// pints the square of i</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"><o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">    }<o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">   <o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">    </span><b><span style="color: green; font-family: "consolas"; font-size: 11.5pt;">return</span></b><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;"> </span><span style="color: #666666; font-family: "consolas"; font-size: 11.5pt;">0</span><span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">;<o:p></o:p></span></div>
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<span style="color: #1e1e1e; font-family: "consolas"; font-size: 11.5pt;">}<o:p></o:p></span></div>
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<span style="font-size: 16.0pt; line-height: 107%;">The output
of the following program is<o:p></o:p></span></div>
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<span style="font-family: "consolas"; font-size: 14.0pt; line-height: 107%;">0  1  4 
9  16  25  36  49 
64  81  100<o:p></o:p></span></div>
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<span style="font-size: 20.0pt; line-height: 107%;">                                                                                      <o:p></o:p></span></div>
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</div>
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<span style="font-size: 16.0pt; line-height: 107%;">This program has printed squares of numbers starting from 1
to 10. We only need to specify the one statement.<o:p></o:p></span><br />
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<br />
<span style="font-size: 16.0pt; line-height: 107%;"><br /></span></div>

The for loop in C++

The for loop is the easiest loop in C++ to understand. All elements of this loop are in one place contrary to those remaining two (while, d...