R while loop (original) (raw)

Last Updated : 12 Jul, 2025

While loop in R programming language is used when the exact number of iterations of a loop is not known beforehand. It executes the same code again and again until a stop condition is met. While loop checks for the condition to be true or false n+1 times rather than n times. This is because the while loop checks for the condition before entering the body of the loop.

R- While loop Syntax:

while (test_expression) { statement update_expression }

While-loop-in-R

How does a While loop execute?

Control falls into the while loop.
The flow jumps to Condition
Condition is tested.
- If the Condition yields true, the flow goes into the Body.
- If the Condition yields false, the flow goes outside the loop
The statements inside the body of the loop get executed.
Updation takes place.
Control flows back to Step 2.
The while loop has ended and the flow has gone outside.

Important Points about while loop in R language:

It seems to be that while the loop will run forever but it is not true, condition is provided to stop it.
When the condition is tested and the result is false then the loop is terminated.
And when the tested result is True, then the loop will continue its execution.

R - while loop Flowchart:

R - while loopGeeksforgeeks

R - while loop

While Loop in R Programming Examples

Example 1:

R `

R program to illustrate while loop

result <- c("Hello World") i <- 1

test expression

while (i < 6) {

print(result)

update expression

i = i + 1 }

Output:

[1] "Hello World" [1] "Hello World" [1] "Hello World" [1] "Hello World" [1] "Hello World"

Example 2:

R `

R program to illustrate while loop

result <- 1 i <- 1

test expression

while (i < 6) {

print(result)

update expression

i = i + 1 result = result + 1 }

Output:

[1] 1 [1] 2 [1] 3 [1] 4 [1] 5

R - while loop break

Here we will use the break statement in the R programming language. The break statement in R is used to bring the control out of the loop when some external condition is triggered.

R `

R program to illustrate while loop

result <- c("Hello World") i <- 1

test expression

while (i < 6) {

print(result)

if( i == 3){
    break}
# update expression
i = i + 1

}

Output:

[1] "Hello World" [1] "Hello World" [1] "Hello World"

R - while loop next

R `

Set an initial value for a variable

x <- 1

Loop while x is less than 10

while (x < 10) { if (x == 3) { # Skip iteration when x is 3 x <- x + 1 next } print(paste("The current value of x is:", x)) x <- x + 1 }

Print a message after the loop has finished

print("The loop has ended.")

Output

[1] "The current value of x is: 1" [1] "The current value of x is: 2" [1] "The current value of x is: 4" [1] "The current value of x is: 5" [1] "The current value of x is: 6" [1] "The current value of x is: 7" [1] "The current value of x is: 8" [1] "The current value of x is: 9"

In this instance, x's initial value is set to 1 at the beginning. Then, as long as x is less than 10, we continue iterating using a while-loop. We use an if statement inside the loop to see if x equals 3. If so, the loop's current iteration is skipped in favor of the following one using the next statement. If not, we use the x - x + 1 expression to increment x by 1 and output a message stating the current value of x.

The next line instructs R to move on to the next iteration of the loop and skip the current one. based on a condition, over a subset of the loop's iterations without ever leaving the loop.

R While Loop with If .. Else

R `

x <- 1

while (x <= 10) { if (x %% 2 == 0) { print(paste(x, "is even")) } else { print(paste(x, "is odd")) } x <- x + 1 }

Output

[1] "1 is odd" [1] "2 is even" [1] "3 is odd" [1] "4 is even" [1] "5 is odd" [1] "6 is even" [1] "7 is odd" [1] "8 is even" [1] "9 is odd" [1] "10 is even"

In this illustration, we initialize a variable x to 1, and then we iterate through the integers 1 through 10 using a while loop. We utilize an if-else statement inside the loop to determine whether x is even or odd. We publish a message stating that x is even if it is. We print a message noting that x is unusual if it is. Then, until x is more than 10, we increase x by 1 and loop till x is greater than 10.