C Programming: Variables and Loops Quiz

## C Programming: Variables and Loops

## Understanding Variables in C Programming

Variables are named storage locations in a program where values can be stored temporarily. They are declared in C using specific keywords like `int`, `float`, `char`, and `double` followed by the variable name. The value assigned to a variable changes during execution according to the logic of the program. In simple terms, a variable represents a container that holds a value.

```c
// Example of variable declarations
int num;
float pi;
char c;
double salary;

Variables can also hold constant values. These are usually represented using all uppercase letters. The two types of constants are numeric constants and character constants.

Looping in C Programming

Loops are control statements in C that allow us to repeatedly perform a block of code until a certain condition is met. There are primarily three types of loops: for, while, and do-while.

For Loop

The for loop in C consists of four parts: initialization, condition, update statement, and the body. The following example demonstrates their usage:

// Example of for loop
int i;
for (i = 1; i <= 5; i++) {
    printf("%d", i); // This will print numbers from 1 to 5
}

In the above code snippet, we initialize i as 1, set the condition that i should be less than or equal to 5, increment i by 1 after each iteration using the update statement, and finally execute the body which prints the value of i.

While Loop

A while loop executes a block of code repeatedly while its condition remains true. Here's how it works:

// Example of while loop
int j;
j = 1;
while (j < 6) {
    printf("%d", j); // This will also print numbers from 1 to 5
    j++; // Increment j by 1 after each iteration
}

Unlike the for loop, the while loop does not have an explicit counter variable like i. Instead, the condition inside the parentheses determines when the loop should terminate.

Do-While Loop

The do-while loop is similar to the while loop, but it always runs at least once before checking the condition. This can be useful if you want to ensure the condition is fulfilled before exiting the loop.

// Example of do-while loop
int k;
k = 20;
do {
    printf("Enter a number greater than %d: ", k);
    scanf("%d", &k);
} while (k < 18); // If the user enters a number less than 18, the loop continues until they enter something higher

In this case, the code inside the do-while loop runs first before checking whether the condition is true or not. This ensures that some code execution happens regardless of the condition's initial state.