Thread: Extract variable definitions and variable reference from a 'C' program

Hi everyone! I've been assigned a strange project at college. I've been asked to extract variable definitions and references from a given input 'C' program.

Each line in the input program contains respective line number at the beginning and followed by a space, and then the actual code begins.

Consider the following program..

Code:

1 int main()
2 {
3 int a,b,c;
4 printf("Enter the values of a and b\n");
5 scanf("%d%d",&a,&b);
6 c=a+b;
7 printf("The sum of two numbers is %d",c);
8 }

And the input for the program which I'm developing is a 'C' program, in which single line consists of a single statement..
ie, we know that a whole program can be written in a single line. But not in my case, that is once there is a termination(semicolon), the lines following the semi colon is shifted to next line..

Anyways my job is to extract the variable definitions/declarations and variable use/reference in the given input C program..

Consider the above program,
In line number 3, variables a,b and c are declared, hence it has to be printed under the "definition" column of the output..

Similarly in the statement 5, values of a and b are being initialized using a scanf statement, hence variables a and b should be printed under the definition column of the output..

Now consider the statement 6, The value of variable c is being initialized/defined hence c must be printed under the definition column.. At the same time, values of a and b are being used to determine the value of c, hence variables a and b must be printed under the "reference" column of the output..

And lastly, the value of variable c is being referenced/used in the statement 7, hence the variable c has to be printed under the referenced column..

The sample output of the program is as shown below..

Code:

Line Number          Defined Variable        Referenced Variable
_____________________________________________________________________
      1                       --                           --
      2                       --                           --
      3                     a,b,c                         --
      4                       --                           --
      5                      a,b                          --
      6                       c                           a,b
      7                       --                          c
      8                       --                          --

Can anyone tell me how to solve the problem????
Remember, I need to write a C/C++ program for the project..
I need to consider the mathematical expressions, logical expressions, built in function calls, user defined function calls and function definitions as well..

Thanks in advance..

Are you confusing 'defined' with 'reference' ? In your "defined variable" column you list variable 'c' twice. Defining and assigning (writing) and referencing (reading) are three different things.

I agree there seems to be a lot of code there. How about filtering for variables in a relatively simple way. Then seeing if the context was 'define' or 'reference'.

"I need to consider the mathematical expressions, logical expressions, built in function calls, user defined function calls and function definitions as well.." - no not really. You don't want to be put in a position where you need to anticipate every built-in library function, or possible user-written in other code modules that are not immediately visible. You need to work on a generic variable detector.