R – while loop
While loop in R programming language is used when the exact number of iterations of 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
} 
How does a While loop execute?
- Control falls into the while loop.
- The flow jumps to Condition
- Condition is tested.
- If Condition yields true, the flow goes into the Body.
- If 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 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 loop is terminated.
- And when the tested result is True, then loop will continue its execution.
R – while loop Flowchart:
While Loop in R Programming Examples
Example 1:
R
# R program to illustrate while loopresult <- c("Hello World")i <- 1# test expressionwhile (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 loopresult <- 1i <- 1# test expressionwhile (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. 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 loopresult <- c("Hello World")i <- 1# test expressionwhile (i < 6) { print(result) if( i == 3){ break} # update expression i = i + 1} |
Output:
[1] "Hello World" [1] "Hello World" [1] "Hello World"
