Thread: Code Translation

Hi,
I desperately need advice on planning a program that performs Pascal-to-C++ code conversion. I'm including a sample Pascal program with its C++ equivalent. You don't need to know Pascal - if you can help me plan a program that'll be able to convert this sample code, I'll be more than satisfied.
Leaving out the reading-from-file and writing-to-new-file parts of it, (just knowing that it'll convert line by line) how should the program be structured? (How should the conversion be divided, what should each division do?)

I will be forever thankful to anyone who helps me with this program!

Linette


Pascal code:

Code:

program pas (input, output); 
uses    crt;
var
        avg: real;
        count, sum, grd, n : integer;

        procedure readint (lo,hi : integer; var x: integer);
	var       nothing : char;    {here for no reason}
        begin
             readln(x);
             while (x<lo) or (x>hi) do
             begin
               writeln (x, ' is not an acceptable grade.');
               write ('Enter a grade: ');
               readln (x);
             end;
        end;

begin
     clrscr;
     write ('How many grades? ');
     readln (n);
     writeln;
     sum := 0;
     for count := 1 to n do
     begin
          write ('Enter a grade: ');
          readint (0,100,grd);
          sum := sum + grd;
     end;
     avg := sum / n;
     writeln;
     writeln ('The total is ',sum);
     writeln ('The average is ',avg:5:2);  {don't worry about the formatting yet}
     readkey;
end.

C++ equivalent:

Code:

#include <iostream.h>
#include <conio.h>

void readint (double lo, double hi, double &x) {
	char nothing; /* here for no reason */
	cin >> x;
	while ( (x<lo) || (x>hi) ) {
		cout << x << " is not an acceptable grade." << endl;
		cout << "Enter a grade: ";
		cin >> x;
	}
	return;
}

void main () {
	double avg;
	int count;
	double sum;
	double grd;
	int n;
	clrscr ();
	cout << "How many grades? ";
	cin >> n;
	cout << "\n";
	sum = 0;
	for (count=1; count<=n; count++) {
		cout << "Enter a grade: ";
		readint (0,100,grd);
		sum = sum + grd;
	}
	avg = sum / n;
	cout << "\n";
	cout << "The total is " << sum << endl;
	cout << "The average is " << avg << endl;  /*don't worry about the formatting yet*/
	return;
}

Wow, I can't believe I got so many replies!..

Yeah, whats it like to be so popular

This cannot be done in simple text substitution. Well, maybe it can be done this way. How complex should it be ? What is it for ? Does it have to translate this program only, or should it be a general translator ?

You will need to get this as one long string and tokenize it. Make a linked list of words and put all the words of the pascal code in there. From there you can then start translating it.

If it has to be more complicated, maybe books about building parsers and compilers might help.