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R – while loop

  • Last Updated : 27 Oct, 2021

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
}  

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 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-flowchart-in-R

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. 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"



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