Boloji.com - A Study in Diversity - News, Views, Analysis, Literature, Poetry, Features - Express Yourself SignUp
Boloji.com

Channels

In Focus

 
Analysis
Cartoons
Education
Environment
Going Inner
Opinion
Photo Essays
 
 

Columns

 
A Bystander's Diary
Business
My Word
PlainSpeak
Random Thoughts
 
 

Our Heritage

 
Architecture
Astrology
Ayurveda
Buddhism
Cinema
Culture
Dances
Festivals
Hinduism
History
People
Places
Sikhism
Spirituality
Vastu
Vithika
 
 

Society & Lifestyle

 
Family Matters
Health
Parenting
Perspective
Recipes
Society
Teens
Women
 
 

Creative Writings

 
Book Reviews
Ghalib's Corner
Humor
Individuality
Literary Shelf
Love Letters
Memoirs
Musings
Quotes
Ramblings
Stories
Travelogues
Workshop
 
 

Computing

 
CC++
Computing Articles
Flash
Internet Security
Java
Linux
Networking
 
 
Computing Articles Share This Page
The DO Statement
by Sachin Mehta Bookmark and Share

Last time, we embarked on a journey of loops. So let's continue from where we left.

The while statement discussed is an entry-controlled loop structure, in which the loop will not be executed if the test condition comes out to be false. But in some situations it might be necessary to execute the loop, even if the test-condition fails. So this kind of loops are called the exit-controlled loop structure. This takes the form:

do
{
   body of the loop
}
while (test condition);

Example: 

do
{
   ch = getchar();
   printf("The character entered is %c",ch);
}
while (ch != 'n')

ch is assumed to be a variable of type character. Now the loop is executed first under no test and the input by the user is outputted. Then the entered value would be tested by the condition for further advancement.

The FOR Statement:

The for loop is an entry-controlled loop that provides a more concise loop control structure. The general form of the for loop is:

for (initialization; test-condition ; increment)
{
  body of the loop
}

The execution of the for statement is as follows:

  1. Initialization of the control variables is done first, using assignment statements 
    such as i = 1 and count = 0.  The variables i and count are known as the loop control variables.
       
  2. The value of the control variable is tested using the test-condition. The test-condition is a relational expression, such as i<10 that determines when the loop will exit. If the condition is true, the body of the loop is executed; otherwise the loop is terminated and the execution continues with the statement that immediately follows the loop.
       
  3. When the body of the loop is executed, the control is transferred  back to the for statement after evaluating the last statement in the loop. Now , the control variable is incremented using an assignment statement such as i = i+1 and the new value of the control variable is again tested to see whether it satisfies the loop condition. If the condition is satisfied, the body of the loop is again executed. This process continues till the value of the control variable fails to satisfy the test-condition.    

Example:

for( i = 0; i<10; i = i+1)
{
   printf("%d",i);
}

The for loop will be executed 10 times. Each time a value equal to the current value of i will be printed out. 

Additional Features of for Loop

1. More than one variable can be initialized at a time in the for statement. For example:

for (p=1,n=0; n<18; ++n)  

2. Like the initialization section, the increment section may also have more than one part. 
    For example,

for (a=2,b=30; n <= m; n=n+1,m=m-1)                   
{
p = b/a;
printf("%d ",p);
}

3. It is also permissible to use expressions in the assignment statements of initialization and increment sections. For example 

for (w = (a+b); w>0; w=w/2) is valid.

4. One or more sections in the for statement can be omitted, if necessary. For example

e = 2;
for (; e != 10 ;)
{
   printf("%d",e);
   e = e + 2;
}

Both the initialization and increment sections are omitted in the for statement. In such cases, the sections are left blank. However, the semicolons separating the sections must remain. If the test-condition is not present, the for statement sets up an infinite loop.   

Share This:
15-Feb-2001
More by :  Sachin Mehta
 
Views: 1808      Comments: 0




Name *
Email ID
 (will not be published)
Comment
Verification Code*
Can't read? Reload
Please fill the above code for verification.
 
Top | Computing Articles



 
 
 
 
 
 
2018 All Rights Reserved
 
No part of this Internet site may be reproduced without prior written permission of the copyright holder
.