CompileTimeEvaluation.java

import java.util.*;
public class COCompileTimeEvaluation {

    public static void main(String[] args) {
    	
    	Scanner sc = new Scanner(System.in);
    	System.out.println("Enter number of expressions");
    	int n = sc.nextInt();
    	
    	sc.nextLine();
    	System.out.println("Enter the expression: ");
    	String prog[] = new String[100];
    	for(int i = 0; i < n; i++) {
    		prog[i] = sc.nextLine();
	}
	sc.close();
    	for(int i = 0; i < n; i++) {
    		if(prog[i].contains("=")) {
	    		String tokens[] = prog[i].split("=");
	    		String replaceThis = tokens[0];
	    		String replaceBy = tokens[1];
	    		
	    		for(int j = i+1; j < n; j++) {
	    			prog[j] = prog[j].replace(replaceThis, replaceBy);
	    		}
    		}	
	}

	System.out.println("\nAfter performing Compile Time Evaluation:");
    	for(int i = 0; i < n; i++) {
		System.out.println(prog[i]);
	}

    } 
    
}

/*

OUPUT:

Enter number of expressions
3
Enter the expression:
pi=3.14259
area = pi * r * r;
circumference = 2 * pi * r;

After performing Compile Time Evaluation:
pi=3.14259
area = 3.14259 * r * r;
circumference = 2 * 3.14259 * r;

*/