C++
Loops - while, for and do while loop
In any programming language, loops are used
to execute a set of statements repeatedly until a particular condition is
satisfied.
How it works
A
sequence of statement is executed until a specified condition is true. This
sequence of statement to be executed is kept inside the curly braces { } known as loop body. After every
execution of loop body, condition is checked, and if it is found to be true the
loop body is executed again. When condition check comes out to be false,
the loop body will not be executed.
There are 3 type of loops in C++ language
while loop
for loop
do-while loop
while loop
while loop can be address as an entry
control loop. It is completed in 3 steps.
·
Variable
initialization.(e.g int x=0;)
·
condition(e.g while(
x<=10))
·
Variable
increment or decrement (x++ or x-- or x=x+2)
Syntax:
variable initialization;
while(condition)
{
statements;
variable increment or decrement;
}
for loop
for loop
is used to execute a set of statement repeatedly until a particular condition
is satisfied. we can say it an open ended loop. General format
is,
for(initialization;condition;increment/decrement)
{
statement-block;
}
-block;
}
In for loop
we have exactly two semicolons, one after initialization and second after
condition. In this loop we can have more than one initialization or
increment/decrement, separated using comma operator. for loop
can have only one condition.
do...while loop
In some
situations it is necessary to execute body of the loop before testing the
condition. Such situations can be handled with the help of do-while loop. do statement evaluates the body of the
loop first and at the end, the condition is checked using while statement. General format of do-while loop is,
do
{
// a couple of statements
}
while(condition);
Jumping out of a loop
Sometimes,
while executing a loop, it becomes necessary to skip a part of the loop or to
leave the loop as soon as certain condition becocmes true, that is jump out of
loop. C language allows jumping from one statement to another within a loop as
well as jumping out of the loop.
1) break statement
When
break statement is encountered inside a
loop, the loop is immediately exited and the program continues with the
statement immediately following the loop.
2) continue statement
It causes the
control to go directly to the test-condition and then continue the loop process.
On encountering continue, cursor leave the current cycle of loop, and starts
with the next cycle.
