# C program to find area of rectangle

In this post, you will learn how to write programs using the **C programming language** to find the **area of a rectangle**.

The **area of a rectangle** is the region covered by the rectangle in a two-dimensional plane. A rectangle is a two-dimensional shape that has four sides and four vertices. The area of a rectangle is the number of unit squares that can fit into a rectangle. If we know the width and height of a rectangle, we can easily calculate the area of a rectangle using the following formula.

**Area = Width * Height**

## Simple C program to calculate area of rectangle

In the given **C** program, we have given the **width** and **height** of a rectangle. We calculate the area of the rectangle by multiplying the width and height of the rectangle.

```
#include <stdio.h>
int main()
{
int width=45;
int height=20;
int area=width*height;
printf("Area of the rectangle=%d",area);
}
```

**Output of the above code:**

`Area of the rectangle=900`

## C program to calculate area of rectangle using user input

The given **C** program allows a user to enter the width and height of a rectangle. Next, we calculate the area as per the formula: **Area = width * height**.

```
// C Program to find Area of a Rectangle
#include <stdio.h>
int main()
{
int length, width, area;
//Input length and width of rectangle
printf("Please enter length of rectangle: ");
scanf("%d", &length);
printf("Please enter width of rectangle: ");
scanf("%d", &width);
/* Calculate area of rectangle */
area = length * width;
/* Print area of rectangle */
printf("Area of rectangle = %d", area);
return 0;
}
```

**Output 1**

```
Please enter length of rectangle: 45
Please enter width of rectangle: 2
Area of rectangle = 90
```

**Output 2**

```
Please enter length of rectangle: 23
Please enter width of rectangle: 53
Area of rectangle = 1219
```

## C program to find area of rectangle using user-defined function

In the given **C** program, we have created a user-defined function **areaRectangle()** to calculate the area of a rectangle.

```
// C Program to find Area of a Rectangle using function
#include <stdio.h>
int areaRectangle(int, int);
int main()
{
int length, width, area;
//Input length and width of rectangle
printf("Enter the length : ");
scanf("%d", &length);
printf("Enter the width : ");
scanf("%d", &width);
/* Calculate area of rectangle */
area = areaRectangle(length, width);
/* Print area of rectangle */
printf("The area of the rectangle : %d", area);
return 0;
}
int areaRectangle(int l, int w)
{
return l * w;
}
```

**Output 1**

```
Enter the length : 92
Enter the width : 21
The area of the rectangle : 1932
```

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