Introduction to Loops in C Programming
In C, and all other modern programming languages, iteration statements (also called loops) allow a set of instructions to be repeatedly executed until a certain condition is reached. This condition may be predetermined (as in the for loop) or open-ended (as in the while and do-while loops).
Why Loop is Important ?
Suppose that you need to display a string (e.g., Welcome to atnyla! ) a hundred times. It would be tedious to have to write the following statement a hundred times:
printf("Welcome to atnyla!");
printf("Welcome to atnyla!");
...
...
...
printf("Welcome to atnyla!");So, how do you solve this problem? C hava a powerful feature called a loop that controls how many times an operation or a sequence of operations is performed in succession. Using a loop control statement, you simply tell the computer to display a string a hundred times without having to code the print statement a hundred times, as follows:
Program
#include
void main(){
int count = 0;
while (count < 100) {
printf("Welcome to atnyla! \n");
count++;
}
}Output
Welcome to atnyla!
Welcome to atnyla!
....
....
....
Welcome to atnyla!
Welcome to atnyla!
100 times
Press any key to continue . . .Explanation
The variable count is initially 0 . The loop checks whether count < 100 is true .
If so, it executes the loop body to display the message
Welcome to atnyla!and increments count by 1 .
It repeatedly executes the loop body until count < 100 becomes false.
When count < 100 is false (i.e., when count reaches 100 ),
the loop terminates and the next statement after the loop statement is executed
Another important Example ?
Program
#include
void main(){
int n = 10;
while(n > 0) {
printf("%d \n",n);
n--;
}
}Output
10
9
8
7
6
5
4
3
2
1
Press any key to continue . . .Types of Loop
Java provides mainly three types of loop statements:whileloops, do - whileloops, andforloops.
| Sr.No. | Loop & Description |
|---|---|
| 1 | while loop
Inwhile loopfirst checks the condition if the condition is true then control goes inside the loop body otherwise goes outside of the body. |
| 2 | do...while loop
A do while loop is a control flow statement that executes a block of code at least once, and then repeatedly executes the block, or not, depending on a given condition at the end of the block (in while). |
| 3 | for loop
For Loop is used to execute set of statementsrepeatedlyuntil the condition is true. |
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