Loops in C Programming

What is a Loop?

A loop is a programming construct that allows you to repeat a block of code multiple times.

Instead of writing the same code repeatedly, loops help automate repetitive tasks efficiently.

To perform repetitive tasks without writing redundant code.
To automate processes like traversing arrays, reading input until a condition is met, or repeating calculations.
To reduce errors and improve code maintainability.

There are 3 main types of loops in C:

The for loop is used when the number of iterations is known beforehand.

for (initialization; condition; update) {
    // Code to execute repeatedly
}

Example: Print numbers from 1 to 5

for (int i = 1; i <= 5; i++) {
    printf("%d\n", i);
}

The while loop executes as long as the condition is true.

while (condition) {
    // Code to execute repeatedly
}

Example: Print numbers from 1 to 5

int i = 1;
while (i <= 5) {
    printf("%d\n", i);
    i++;
}

The do-while loop executes the code block at least once, then repeats as long as the condition is true.

do {
    // Code to execute
} while (condition);

Example: Print numbers from 1 to 5

int i = 1;
do {
    printf("%d\n", i);
    i++;
} while (i <= 5);

Loop Type	Execution	Condition Check	When to Use
`for`	Known number of iterations	Before each iteration	When iteration count is known
`while`	Unknown iterations	Before each iteration	Repeat while condition is true
`do-while`	At least once	After each iteration	When code must run at least once

Write a program using a for loop to print the multiplication table of 7 (from 7×1 to 7×10).
Write a program using a while loop to calculate the sum of numbers from 1 to 50.
Write a program using a do-while loop to repeatedly ask the user to enter a number until they enter 0.
Write a program to find the factorial of a number using any loop.