I need a program that reads prefix expression and return its value. the expressi

Question

I need a program that reads prefix expression and return its value. the expression only contains +,* and single digits. For instance: + 5 * 6 7 returns 47, in other words it multiplies 6 * 7 first then adds 5.

See my program below, I am having two errors that I want fix, PLEASE FIX THIS PROGRAM, DO NOT COPY AND PASTE A PROGRAM FROM SOMEWHERE THAT DO NO APPLY TO THIS PROGRAM. THANK YOU.

Ashley:

my program below:

import java.util.Scanner;
public class lab8
{
public static void main (String[] args)
{
char[] a;
a = new char[6];
a[0] = '0';
a[1] = '6';
a[2]= '*';
a[3]= '7';
a[4]='+';
a[5]= '5';
System.out.print(prefixcalc(a,0));
}

public static int prefixcalc(char [] a, int i)
{
if ((int)a[i]>=48&&(int)a[i]<=57)
return (a[i]-'0'); //or `(int)a[i]-48;
{
if ((int)a[i] == ('+'))
return (5+prefixcalc(a[i],i+2));
{
if ((int)a[i] == ('*'))
return (6*prefixcalc(a[i],i+2));
else
return 7;


}


}
}
}

my errors:

2 errors found:

File: S:us210lab8.java [line: 23]
Error: method prefixcalc in class lab7 cannot be applied to given types;
required: char[],int
found: char,int
reason: actual argument char cannot be converted to char[] by method invocation conversion

File: S:csi310lab7.java [line: 26]
Error: method prefixcalc in class lab7 cannot be applied to given types;
required: char[],int
found: char,int
reason: actual argument char cannot be converted to char[] by method invocation conversion

Explanation / Answer

The problem is you are passing a char instead of char [] In two places return (5+prefixcalc(a[i],i+2)); and return (6*prefixcalc(a[i],i+2)); a[i] is a char instead you should pass a return (5+prefixcalc(a,i+2)); return (6*prefixcalc(a,i+2));

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