Question

If i have a C source file and i want to locate a specific local variable within a function and make it global – so another tool is able to process the C file (a tool i didn’t write) what would be the easiest way to do this? I was thinking of using regex, but even that posses it’s own problems. It’s kind of like writing a mini C parser in Java.. a lot of work :S

Are there any libraries that can help make this easier?

For example, say i want to make the variable “i” into a global variable. The user will specify the function name and the variable name (but not the type the variable is – ie. “int”).

I can use regex to find the function – sure. But from there i really don’t know what the best approach would be?… Will CDT plugin help?

Example:

 /* 
  * add.c
  * a simple C program
  *
  */

#include <stdio.h>
#define LAST 10

int main()
{
    int i = 0;
    int sum = 0;

    for ( i = 1; i <= LAST; i++ ) {
      sum += i;
    } /*-for-*/
    printf("sum = %d\n", sum);

    return 0;
}

converted to:

 /* 
  * add.c
  * a simple C program
  *
  */

#include <stdio.h>
#define LAST 10

int i = 0;

int main()
{

    int sum = 0;

    for ( i = 1; i <= LAST; i++ ) {
      sum += i;
    } /*-for-*/
    printf("sum = %d\n", sum);

    return 0;
}

Answer 1

The first thing I would demand is a complete specification of exactly when this is required and why, and how to identify when it is safe to do so without adversely affecting the program semantics. This is a really bad idea. Clearly those who gave you the assignment have no idea of either the implementation complexity, which is immense, or the adverse semantic effects. I am guessing that they will therefore be unable to come up with an adequate specification either, which will ultimately let you out.

I would also draw their attention to this discussion, especially Ira Baxter’s comments. I used to build compilers for a living. It is not a task to learn, or ask about, on a forum.