Loops in C

What are Loops in C?

Loops are control structures in C that allow you to execute a block of code continuously as long as a specific condition is met. They help in creating more efficient and concise code.

Need for Looping Statements in C

• Loops enable the user to repeat the same collection of statements without having to write the same code several times.
• It saves time, and effort, and improves efficiency.
• It lowers the possibility of finding mistakes during compilation.
• Loops make code more clear and understandable, particularly when dealing with complex logic or big data sets.
• It promotes code reuse.
• Loops are useful for traversing data structures like arrays or linked lists.

Types of Loop in C

There are 3 Types of Loops in C:

1. for loop
2. while loop
3. do while loop

For Loop

A for loop is a control structure that allows a sequence of instructions to be performed for a predetermined number of iterations. It's an entry-controlled loop. It has three sections: index declaration, condition (boolean expression), and update statement. The for loop is useful when you know the precise number of iterations.

How does the for loop work?

• The initialization statement is only used once.
• Next, the test expression is evaluated. If the test expression returns false, the for loop is terminated.
• If the test expression is true, the statements in the for loop's body are executed, and the update expression is updated.
• Again, the test expression is examined.
• This operation continues until the test expression is false. When the test expression is false, the loop ends.

Infinite For Loop

An infinite loop refers to a loop that runs continuously. In short, in the for loop, if the test condition (check_condition) is not specified, it is presumed to be true by default. As a result, the condition never turns false.

Advantages of the For Loop

• Allows code reusability.
• The code size decreases.
• Traversing data structures such as arrays and strings becomes simple.

Disadvantages of using For Loops

• Cannot skip any elements while traversing.
• Only one requirement is followed.

While Loop

A while loop executes a statement or a group of statements until the provided expression returns false. The while loop is useful when you don't know the exact number of iterations.

Working of the While Loop

• When the program first enters the loop, the test condition will be assessed.
• If the test condition is false, the loop's body is skipped and the program continues.
• If the expression returns true, the body of the loop will be run.
• After executing the body, the program will proceed to the first step. The operation will continue till the test expression is true.

Infinite While Loop in C

In C programming, an infinite while loop is a loop structure that executes endlessly until it encounters a break statement or a condition that terminates it. It is referred to as "infinite" because, unlike other loops, it has no fixed ending.

Do While Loop

A Do While loop is similar to a while loop, but it evaluates the expression after the code block is executed.​ Always executes at least once. Useful for one-time execution with conditional dependencies.

How does the Do-While Loop work?

• The do-while loop executes the body first before checking the test condition, unlike other loops that verify the test condition first.
• The do-while loop, also known as the exit-controlled or post-tested loop, is named for this attribute.
• When the test condition is true, the program control returns to the beginning of the loop, and the body is executed once more.
• This method is repeated until the test condition is met.
• When the test condition is false, the program moves on to the next sentence after the do-while loop.

Advantages of Do While Loop

• A do-while loop has a simple structure that everybody can understand.
• Regardless of the condition, the code inside a do-while loop gets run at least once in its lifetime.
• The code inside a do-while loop will continue to run until the condition is met.