Explain different looping statement with syntax and examples
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Answer:
Types of Loops in C
Depending upon the position of a control statement in a program, looping statement in C is classified into two types:
1. Entry controlled loop
2. Exit controlled loop
In an entry control loop in C, a condition is checked before executing the body of a loop. It is also called as a pre-checking loop.
In an exit controlled loop, a condition is checked after executing the body of a loop. It is also called as a post-checking loop.
Sample Loop
The control conditions must be well defined and specified otherwise the loop will execute an infinite number of times. The loop that does not stop executing and processes the statements number of times is called as an infinite loop. An infinite loop is also called as an "Endless loop." Following are some characteristics of an infinite loop:
1. No termination condition is specified.
2. The specified conditions never meet.
The specified condition determines whether to execute the loop body or not.
'C' programming language provides us with three types of loop constructs:
1. The while loop
2. The do-while loop
3. The for loop
Sr. No. Loop Type Description
1. While Loop In while loop, a condition is evaluated before processing a body of the loop. If a condition is true then and only then the body of a loop is executed.
2. Do-While Loop In a do...while loop, the condition is always executed after the body of a loop. It is also called an exit-controlled loop.
3. For Loop In a for loop, the initial value is performed only once, then the condition tests and compares the counter to a fixed value after each iteration, stopping the for loop when false is returned.
While Loop in C
A while loop is the most straightforward looping structure. While loop syntax in C programming language is as follows:
Syntax of While Loop in C:
while (condition) {
statements;
}
It is an entry-controlled loop. In while loop, a condition is evaluated before processing a body of the loop. If a condition is true then and only then the body of a loop is executed. After the body of a loop is executed then control again goes back at the beginning, and the condition is checked if it is true, the same process is executed until the condition becomes false. Once the condition becomes false, the control goes out of the loop.
After exiting the loop, the control goes to the statements which are immediately after the loop. The body of a loop can contain more than one statement. If it contains only one statement, then the curly braces are not compulsory. It is a good practice though to use the curly braces even we have a single statement in the body.
In while loop, if the condition is not true, then the body of a loop will not be executed, not even once. It is different in do while loop which we will see shortly.
Following program illustrates while loop in C programming example:
#include<stdio.h>
#include<conio.h>
int main()
{
int num=1; //initializing the variable
while(num<=10) //while loop with condition
{
printf("%d\n",num);
num++; //incrementing operation
}
return 0;
}
Output:
1
2
3
4
5
6
7
8
9
10
The above program illustrates the use of while loop. In the above program, we have printed series of numbers from 1 to 10 using a while loop.
Example of While Loop in C Programming
While Loop in C Programming
We have initialized a variable called num with value 1. We are going to print from 1 to 10 hence the variable is initialized with value 1. If you want to print from 0, then assign the value 0 during initialization.
In a while loop, we have provided a condition (num<=10), which means the loop will execute the body until the value of num becomes 10. After that, the loop will be terminated, and control will fall outside the loop.
In the body of a loop, we have a print function to print our number and an increment operation to increment the value per execution of a loop. An initial value of num is 1, after the execution, it will become 2, and during the next execution, it will become 3. This process will continue until the value becomes 10 and then it will print the series on console and terminate the loop.
\n is used for formatting purposes which means the value will be printed on a new line.
Do-While loop in C
A do...while loop in C is similar to the while loop except that the condition is always executed after the body of a loop. It is also called an exit-controlled loop.
Syntax of do while loop in C programming language is as follows:
Syntax of Do-While Loop in C:
do {
statements
} while (expression);
As we saw in a while loop, the body is executed if and only if the condition is true. In some cases, we have to execute a body of the loop at least once even if the condition is false. This type of operation can be achieved by using a do-while loop.
Explanation:
Explanation:
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