Firstly, ?n this program ,I have also extend the% operation to calculate the remainder.

Secondly, add an exponentiation operation(^).

The result should be as follows. 2 * 3 ^ 3 = 54.

( 2 * 3 ) ^ 3 = 216.

Thirdly, support unary operations.

- 5 + 100 = or ( - 32 + ( - 1 ) ) =

It should be make it possible to calculate

Source code :

public class Exp {

String[] cal;

String token;

int idx;

public Exp(String[] eee,int iii) { // constructor

// formal marameter --> instance value

cal = eee;

idx = iii;

token = cal[iii];

}

int expression() { /* Expression */

char k;

int num1=term();

while ( (token.charAt(0)== '+') || (token.charAt(0) == '-') ) {

k = token.charAt(0);

token = cal[++idx];

int num2=term();

if (k == '+') { num1=num1+num2; }

else { num1=num1-num2; }

}

return num1;

}

int term() { /* Term */

char k;

int num1=factor();

while ( (token.charAt(0) == '*') || (token.charAt(0) == '/') ) {

k = token.charAt(0);

token = cal[++idx];

int num2=factor();

if (k == '*') { num1=num1*num2; }

else { num1=num1um2; }

}

return num1;

}

int factor() { /* Factor */

int num=0;

if ( (token.charAt(0)>='0') && (token.charAt(0)

num = Integer.parseInt(token); /* String --> int */

token = cal[++idx];

} else if (token.charAt(0) == '(') { /* ( expression ) */

token = cal[++idx];

num = expression();

if (token.charAt(0)!=')') System.out.println(" ) expected. ");

token = cal[++idx];

} else {

System.out.println("syntax error ");

}

return num;

}

}

Main program source code :

import java.io.*;

public class Cal {

public static void main(String[] args)throws IOException {

System.out.println("input expression with = ");

BufferedReader r = new BufferedReader(new InputStreamReader(System.in));

String s = r.readLine();

String[] token = s.split(" "); // one line --> token[] by " "

int n=token.length; // number of token

if (n

else {

for (int i=0 ; i

System.out.print(token[i]+" ");

}

Exp exp = new Exp(token, 0); // construct instance exp

int ans = exp.expression(); // calculate expression

System.out.println(" " + ans);/* answer */

}

}

}

Note: When inputting data from the keyboard, spaces must be written between all data.

(215-2*2*2*2*2?????????????? :- { } :: = { :: = { ^ ::?01 1 , 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9