Comp Sci FORTRAN Help: Using Functions and Arrays

AI Thread Summary
The discussion focuses on improving a FORTRAN program that functions as a basic calculator. Key points include the need to consolidate multiple input functions into a single READDATA function that captures two real numbers and a choice character from the user. Participants noted issues with function calls and variable naming, suggesting clearer names and reducing unnecessary variables to enhance code clarity. The user also seeks guidance on keeping the cursor on the same line after a WRITE statement when prompting for input. Overall, the conversation emphasizes refining the program structure and addressing specific coding challenges.
mattmac.nuke
Messages
22
Reaction score
0
Alright, so I've updated it once more... The only thing I need to do is figure out how to convert the functions x_data, y_data and choi_1 that store all 3 of the inputs I need for the main program and other functions.

program calculator
IMPLICIT NONE
REAL :: addition, subtraction, multiplication, division, x, y, j, k, x_data, y_data !x = A, y = B
CHARACTER :: choice, a, b, c, d, l, choi_1WRITE (*,*) ' '
WRITE (*,*) 'LAB 6- Baby Calculator'
WRITE (*,*) '----------------------'j = x_data(x)
k = y_data(y)
l = choi_1(choice)

SELECT CASE (l)
CASE ('A','a')
WRITE (*,*) 'A+B = ', addition (x, y)
CASE ('B','b')
WRITE (*,*) 'A-B = ', subtraction (x, y)
CASE ('C','c')
WRITE (*,*) 'A*B = ', multiplication (x, y)
CASE ('D','d')
WRITE (*,*) 'A/B = ', division(x, y)
END SELECT

end program calculator

CHARACTER FUNCTION choi_1 (choice)
IMPLICIT NONE
CHARACTER :: choice
WRITE (*,*) ' A) A+B'
WRITE (*,*) ' B) A-B'
WRITE (*,*) ' C) A*B'
WRITE (*,*) ' D) A/B'
WRITE (*,*) 'Enter choice:'
READ (*,*) choice
choi_1 = choice
END FUNCTION choi_1

REAL FUNCTION x_data (x)
IMPLICIT NONE
REAL :: x
WRITE (*,*) 'Enter a value A:'
READ (*,*) x
x_data = x
END FUNCTION x_data

REAL FUNCTION y_data (y)
IMPLICIT NONE
REAL :: y
WRITE (*,*) 'Enter a value B:'
READ (*,*) y
y_data = y
END FUNCTION y_dataREAL FUNCTION addition (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
addition = x + y
END FUNCTION addition

REAL FUNCTION subtraction (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
subtraction = x - y
END FUNCTION subtraction

REAL FUNCTION multiplication (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
multiplication = x*y
END FUNCTION multiplication

REAL FUNCTION division (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
IF ( y == 0) THEN
division = 0
ELSE
division = x/y
END IF
END FUNCTION division
 

Attachments

Last edited:
Physics news on Phys.org
mattmac.nuke said:
Alright, so I've updated it once more... The only thing I need to do is figure out how to convert the functions x_data, y_data and choi_1 that store all 3 of the inputs I need for the main program and other functions.

program calculator
IMPLICIT NONE
REAL :: addition, subtraction, multiplication, division, x, y, j, k, x_data, y_data !x = A, y = B
CHARACTER :: choice, a, b, c, d, l, choi_1


WRITE (*,*) ' '
WRITE (*,*) 'LAB 6- Baby Calculator'
WRITE (*,*) '----------------------'


j = x_data(x)
k = y_data(y)
l = choi_1(choice)

SELECT CASE (l)
CASE ('A','a')
WRITE (*,*) 'A+B = ', addition (x, y)
CASE ('B','b')
WRITE (*,*) 'A-B = ', subtraction (x, y)
CASE ('C','c')
WRITE (*,*) 'A*B = ', multiplication (x, y)
CASE ('D','d')
WRITE (*,*) 'A/B = ', division(x, y)
END SELECT

end program calculator

CHARACTER FUNCTION choi_1 (choice)
IMPLICIT NONE
CHARACTER :: choice
WRITE (*,*) ' A) A+B'
WRITE (*,*) ' B) A-B'
WRITE (*,*) ' C) A*B'
WRITE (*,*) ' D) A/B'
WRITE (*,*) 'Enter choice:'
READ (*,*) choice
choi_1 = choice
END FUNCTION choi_1

REAL FUNCTION x_data (x)
IMPLICIT NONE
REAL :: x
WRITE (*,*) 'Enter a value A:'
READ (*,*) x
x_data = x
END FUNCTION x_data

REAL FUNCTION y_data (y)
IMPLICIT NONE
REAL :: y
WRITE (*,*) 'Enter a value B:'
READ (*,*) y
y_data = y
END FUNCTION y_data


REAL FUNCTION addition (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
addition = x + y
END FUNCTION addition

REAL FUNCTION subtraction (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
subtraction = x - y
END FUNCTION subtraction

REAL FUNCTION multiplication (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
multiplication = x*y
END FUNCTION multiplication

REAL FUNCTION division (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
IF ( y == 0) THEN
division = 0
ELSE
division = x/y
END IF
END FUNCTION division

You're missing the READDATA function, so there should be a function with this name. From your PDF, the specification is:
Create a FUNCTION READDATA that will ask the user to enter real numbers A and B and a character CHOICE and stores that data in variables A and B and returns CHOICE.

Instead of having two functions - x_data and y_data - that each read a number from input, write a single function with two parameters that returns a character. This function should prompt the user to enter two numbers and a character that represents the choice of operation.
 
I've written it as one function now, but after making a choice selection it tells me I'm missing a left parenthesis in format.

program calculator
IMPLICIT NONE
REAL :: addition, subtraction, multiplication, division, x, y, j, k, x_data, y_data !x = A, y = B
CHARACTER :: choice, a, b, c, d, l, choi_1


WRITE (*,*) ' '
WRITE (*,*) 'LAB 6- Baby Calculator'
WRITE (*,*) '----------------------'


READ choi_1(x, y, choice)

SELECT CASE (l)
CASE ('A','a')
WRITE (*,*) 'A+B = ', addition (x, y)
CASE ('B','b')
WRITE (*,*) 'A-B = ', subtraction (x, y)
CASE ('C','c')
WRITE (*,*) 'A*B = ', multiplication (x, y)
CASE ('D','d')
WRITE (*,*) 'A/B = ', division(x, y)
END SELECT

end program calculator



CHARACTER FUNCTION choi_1 (x, y, choice)
IMPLICIT NONE
CHARACTER :: choice
REAL :: x, y
WRITE (*,*) 'Enter a value A:'
READ (*,*) x
WRITE (*,*) 'Enter a value B:'
READ (*,*) y
WRITE (*,*) ' A) A+B'
WRITE (*,*) ' B) A-B'
WRITE (*,*) ' C) A*B'
WRITE (*,*) ' D) A/B'
WRITE (*,*) 'Enter choice:'
READ (*,*) choice
choi_1 = choice
END FUNCTION choi_1

REAL FUNCTION addition (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
addition = x + y
END FUNCTION addition

REAL FUNCTION subtraction (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
subtraction = x - y
END FUNCTION subtraction

REAL FUNCTION multiplication (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
multiplication = x*y
END FUNCTION multiplication

REAL FUNCTION division (x, y)
IMPLICIT NONE
REAL, INTENT(IN) :: x, y
IF ( y == 0) THEN
division = 0
ELSE
division = x/y
END IF
END FUNCTION division
 
It's this line:
READ choi_1(x, y, choice)

This is not how to call this function. What you want is something like
Code: 
choice = choi_1(x, y, choice)

BTW, you have way too many character variables.
Code: 
CHARACTER :: choice, a, b, c, d, l, choi_1
Get rid of a, b, c, d, and l. You aren't using a, b, c, or d, so they should not be in your program.

You also have way too many numeric variables; namely, x, y, j, k, x_data, y_data. Get rid of all but two of these. Having extra variables makes your program needlessly confusing, especially to you.

Also, you should pick a better name for your function than choi_1, which is silly. A better name would be GetInput.
 
When calling a FUNCTION, the syntax is VARIABLE = FUNCTION (Arg1. Arg2, ...)

In the main program section, your FUNCTION calls need correction.

Also, you have READ CHOI_1 () and CHARACTER FUNCTION CHOI1 (). You cannot have the same name assigned to a variable and a FUNCTION at the same time.
 
SteamKing said:
When calling a FUNCTION, the syntax is VARIABLE = FUNCTION (Arg1. Arg2, ...)
Another possibility is to use the returned value from the function, such as in a call to WRITE; e.g.,
WRITE *,* ADDITION(x, y)
SteamKing said:
In the main program section, your FUNCTION calls need correction.
The one in the READ statement definitely needs to be fixed. The others are OK.
SteamKing said:
Also, you have READ CHOI_1 () and CHARACTER FUNCTION CHOI1 (). You cannot have the same name assigned to a variable and a FUNCTION at the same time.
 
I really appreciate all the help guys! I actually wound up debugging it during class. I discovered that I can reference the function in my case statements, where all 3 of the data inputs can be used in the arguments and computations. The TA's were amazed that it worked...

Now I have a slightly trivial question, you know how the cursor moves to the next line following a WRITE statement where there is a READ execution, well I need for the cursor to remain on the same line in which the WRITE statement was made. I believe the slash descriptor is used to do this, but I can't seem to apply it correctly, could you perhaps show me a simple example of it's use, where the user is prompted to enter a simple real number?
 

Similar threads

Comp Sci Can‘t call a subroutine name in a subroutine in Fortran90
Replies
7
Views
2K
How to read a column of data into Fortran without arrays? (Fortran 77)
Replies
7
Views
3K
Comp Sci Creating 2D Arrays with Pointers in C | Efficient Memory Allocation
Replies
17
Views
2K
Comp Sci Dynamic Link Library, Compaq Visual Fortran 6.6 & Module
Replies
5
Views
2K
Comp Sci Help with solving first order ODE using a simple Fortran code, please
Replies
4
Views
2K
Comp Sci Multiplication of two 2x2 matrices in Fortran
Replies
2
Views
6K
Comp Sci Real step-size in do loop-fortran
Replies
3
Views
7K
Fortran How do I create a pointer to an element of an array with a variable index?
Replies
20
Views
2K
Comp Sci Need help with Fortran homework -- Error: Invalid form of PROGRAM statement
Replies
4
Views
3K
Comp Sci FORTRAN Help: Functions and Subroutines
Replies
1
Views
3K

Hot Threads

Recent Insights

Back
Top