We can calculate area of circle if we know the value of its radius. So using that, we shall write the logic in c program to calculate the area of a circle, and we will us math.h library functions in this program.
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- #include < stdio.h >
- #include < math.h >
- int main()
- {
- float radius;
- printf("Enter radius of circle\n");
- scanf("%f", &radius);
- printf("Area of circle is %f \n", (M_PI * pow(radius, 2)));
- return 0;
- }
Output:
Enter radius of circle
2.0
Area of circle is 12.566371
Scanf(): For user input
In above c program we are asking user to enter the values for variable a and b. You can know more about scanf() method/function in this video tutorial: Using Scanf in C Program
Calculate Area of a Circle using math.h library: C
math.h library file has a constant M_PI which has the value of PI. Since it’s a constant variable we can not change its value in our program. We’re also using pow() method/function present in math.h header file.
Formula for calculating Area of a circle
Formula for calculating Area of a circle is PI * radius * radius. We take value of radius from user and using above formula calculate area of the circle and output result to the console window. Since we’re using math.h library file we use M_PI and pow() methods for the expression.
i.e., area = M_PI * pow(radius, 2);
For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert