Question

This is Force 2.0 with Fortran 77:

! Program to find the area and perimeter of a circle
program circle
implicit none

! Variable declaration
real :: area, perimeter, radius
real parameter :: pi = 3.142

! Calculating the area
write(*,*) 'Enter the radius of a circle'
read(*,*)radius
area = pi * radius **2
write(*,*) 'The area of the circle is:', area

!Calculating the perimeter
perimeter = 2*pi*radius
write(*,*) 'The perimeter of the circle is:', perimeter
PAUSE
end program circle

This program must be done with and without functions. Also, I'd like the errors to be fixed

Answer 1

Without Function:

Code:

! Program to find the area and perimeter of a circle
program circle
implicit none

! Variable declaration
real :: area, perimeter, radius, pi   
pi = 3.142

! Calculating the area
write(*,*) 'Enter the radius of a circle'   
read(*,*)radius
area = pi * radius **2
write(*,*) 'The area of the circle is:', area

!Calculating the perimeter
perimeter = 2*pi*radius
write(*,*) 'The perimeter of the circle is:', perimeter
PAUSE
end program circle

Image of the Code:

Image of Input and Output:

Explanation: Declared pi as a real variable and initialized its value. Error was that pi was not declared as real variable.

With Function:

Code:

program circle

real :: area, radius, perimeter
write(*,*) 'Enter the radius of a circle'   
read(*,*)radius
area = area_circle(radius)

perimeter = perimeter_circle(radius)

Print *, "The area of a circle is:"
Print *, area

Print *, "The perimeter of a circle is:"
Print *, perimeter

end program circle

function area_circle (r)

  
implicit none

  
real :: area_circle   

! local variables
real :: r   
real :: pi

pi = 3.142
area_circle = pi * r**2

end function area_circle

function perimeter_circle (r)

  
implicit none

  
real :: perimeter_circle   

! local variables
real :: r   
real :: pi

pi = 3.142
perimeter_circle = pi * r * 2

end function perimeter_circle

Image of the Code:

Image of the Input and Output:

Explanation: We have created 2 functions area_circle and area_perimeter and called the functions to get the answer.

If the answer helped please upvote. It means a lot. For any query comment below.