Loops
are such an important programming constructs for various object oriented
languages that they cannot be neglected. All of us are aware of the looping
constructs that we have in programming languages like C and C++. We have three
basic loops:
- For
loop
- While
loop
- Do
while loop
Why Loops are Important?
- Loops
find extensive use in programming and they are a means to tell the program to
keep executing a set of statements until some break condition is encountered.
- Loops
come to be a very handy tool when it comes to the repetition of the whole block
of code.
- It can be done to reduce the length of the code and the task of the programmer or
developer of writing the same code again and again innumerable times.
- In some
cases it also happens that the number of times for which the loop is to be
executed is obtained from the user, in such cases looping of the particular
block of code becomes extremely important.
-There are many software programs or
applications that perform very complex tasks or calculations all by the virtue
of the looping constructs.
Before
taking on the loops in to your software program you should be well versed with
the true and false concept of the programming language that you are using. Let
us discuss all the above mentioned three loops one by one:
1. For Loop:
Here’s the
syntax of the for loop:
For (initialization
of the variable; test condition; increment condition)
{
Statement
1;
Statement
2; (code to be
executed)
.
.
.
Statement
n;
}
In
the expression for the initialization of the variable one can declare the
variable for the loop and initialize it with the required value. Secondly the
test condition is responsible for checking the whether the loop should be
executed or not on the basis of the true or false value. The increment
condition lastly helps the loop to increment the value of the initialized
variable. All of these 3 expressions are separated from each other by
semicolon. An empty condition is evaluated to false value.
2. While Loop:
Here’s the syntax for the while loop:
While(
test condition)
{
Statement
1;
.
.
Statement
n;
}
According
to some programmers the while loops are perhaps the easiest to operate. While
loops are supposed to be entry controlled loop since the condition is checked
up on the entry itself and based on its true value it is executed. While loops
are somewhat like the for loops except that they contain the initialization
expression and the update expression inside their body. But the drawback with
this loop is that it is quite length. This loop won’t allow the execution of
the statements even once if the test condition is evaluated to be false.
3. Do while loop
Here’s
the syntax for the do – while loop:
Do
{
Statement
1;
Statement
2;
.
.
.
Statement
n;
}
while (test condition)
This
loop holds good for the programs in which the execution of a particular block
of statements is required at least once irrespective of whether the test
condition is true or false. The test condition is encountered in the last and
is evaluated. If it is found to be false, then the loop won’t be eligible for a
second iteration. Because of this factor the do while loop is commonly known as
the exit controlled lop.
