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Ruby Loops

Ruby loops: Here, we are going to learn about the looping statements in Ruby programming language with syntax and examples.
Submitted by Hrithik Chandra Prasad, on July 28, 2019

Ruby Loops

Loops are comprised of sequentially group instructions which are executed repeatedly until a certain condition is met. Loops provide great help in making the programmer's task easier.

Types of looping statements in Ruby

Ruby supports the following types of loops:

1. The while loop
2. The for loop
3. The do...while loop
4. The until loop

1) The while loop

In the while loop, the condition for which the loop will run is provided at the top with while keyword. It is one of the forms of the Entry control loop and the pointer gets out when the specified condition is met.

When the number of repetitions is not fixed, it is recommended to use while loop.

Syntax:

    while (condition )
        # code to be executed
    end

Example:

num=5
while num!=0
	puts "Number is greater than zero"
	num-=1
end

Output

Number is greater than zero
Number is greater than zero
Number is greater than zero
Number is greater than zero
Number is greater than zero

In the above code, you can observe that the number of iterations was not fixed. It was dependent upon variable which is specified in the condition.

2) The for loop

for loop is different from while loop only in the context of syntax otherwise both of them are having the same functionality. It is one of the forms of the Entry control loop and the number of iterations must be specified before the execution of the loop. It repeats over a given range of numbers.

Syntax:

    for variable_name[, variable...] in expression [do]
        # code to be executed
    end

Example:

i = "Includehelp"
for l in 1..7 do
    puts i 
end

Output

Includehelp
Includehelp
Includehelp
Includehelp
Includehelp
Includehelp
Includehelp

3) The do...while loop

It is the kind of Exit control loop. It is very identical to while loop but with a difference that the condition is tested after the execution of specified statements. If you want that the expressions must execute at least for once, you should go for do...while loop.

Syntax:

    loop do
        # code block
        break if Condition
    end

Example:

num = 0
loop do 
	puts "Includehelp.com"
	num+=1

	if num==8
		break
	end
end

Output

Includehelp.com
Includehelp.com
Includehelp.com
Includehelp.com
Includehelp.com
Includehelp.com
Includehelp.com
Includehelp.com

4) The until loop

until loop is the antonym of while loop as per the functionality. While loop is terminated when the condition becomes false but the until loop is terminated when the Boolean expression evaluates to be true. It is one of the examples of Entry control loop where the condition is specified before the execution of expressions.

Syntax:

    until conditional [do]
        # code to be executed
    end

Example:

num = 8
until num == 13 do
	puts "Hi there! Welcome to the tutorial"
	num+=1
end

Output

Hi there! Welcome to the tutorial
Hi there! Welcome to the tutorial
Hi there! Welcome to the tutorial
Hi there! Welcome to the tutorial
Hi there! Welcome to the tutorial