ok everything works good outside if i make .java of the classes with a main app
but when i put them together my Postfix one has a problem.
if you are confused just look at the main method
thats where the probelm arises. the thing is after i convert infix to postfix i output it
then i enter that output as input for evaluation of postfix. but according to the compiler its not of type string. PLEASE HELP
import java.io.*; // for I/O
class Stacky
{
private int maxSize;
private int[] stackArray;
private int top;
//--------------------------------------------------------------
public Stacky(int size) // constructor
{
maxSize = size;
stackArray = new int[maxSize];
top = -1;
}
//--------------------------------------------------------------
public void push(int j) // put item on top of stack
{ stackArray[++top] = j; }
//--------------------------------------------------------------
public int pop() // take item from top of stack
{ return stackArray[top--]; }
//--------------------------------------------------------------
public int peek() // peek at top of stack
{ return stackArray[top]; }
//--------------------------------------------------------------
public boolean isEmpty() // true if stack is empty
{ return (top == -1); }
//--------------------------------------------------------------
public boolean isFull() // true if stack is full
{ return (top == maxSize-1); }
//--------------------------------------------------------------
public int size() // return size
{ return top+1; }
//--------------------------------------------------------------
public int peekN(int n) // peek at index n
{ return stackArray[n]; }
//--------------------------------------------------------------
public void displayStack(String s)
{
System.out.print(s);
System.out.print("Stack (bottom-->top): ");
for(int j=0; j<size(); j++)
{
System.out.print( peekN(j) );
System.out.print(' ');
}
System.out.println("");
}
//--------------------------------------------------------------
}
class StackX
{
private int maxSize;
private char[] stackArray;
private int[] stackArray1;
private int top;
public StackX(int s) // constructor
{
maxSize = s;
stackArray = new char[maxSize];
top = -1;
}
public void push1(int j) // put item on top of stack
{ stackArray1[++top] = j; }
public void push(char j) // put item on top of stack
{ stackArray[++top] = j; }
public char pop() // take item from top of stack
{ return stackArray[top--]; }
public int peek1() // peek at top of stack
{ return stackArray1[top]; }
public char peek() // peek at top of stack
{ return stackArray[top]; }
public boolean isEmpty() // true if stack is empty
{ return (top == -1); }
public int size() // return size
{ return top+1; }
public int peekN1(int n) // peek at index n
{ return stackArray[n]; }
public char peekN(int n) // return item at index n
{ return stackArray[n]; }
public void displayStack(String s)
{
System.out.print(s);
System.out.print("Stack (bottom-->top): ");
for(int j=0; j<size(); j++)
{
System.out.print( peekN(j) );
System.out.print(' ');
}
System.out.println("");
}
} // end class StackX
////////////////////////////////////////////////////////////////
class InToPost // infix to postfix conversion
{
private StackX theStack;
private String input;
private String output = "";
public InToPost(String in) // constructor
{
input = in;
int stackSize = input.length();
theStack = new StackX(stackSize);
}
public String doTrans() // do translation to postfix
{
for(int j=0; j<input.length(); j++) // for each char
{
char ch = input.charAt(j); // get it
theStack.displayStack("For "+ch+" "); // *diagnostic*
switch(ch)
{
case '+': // it's + or -
case '-':
gotOper(ch, 1); // go pop operators
break; // (precedence 1)
case '*': // it's * or /
case '/':
gotOper(ch, 2); // go pop operators
break; // (precedence 2)
case '(': // it's a left paren
theStack.push(ch); // push it
break;
case ')': // it's a right paren
gotParen(ch); // go pop operators
break;
default: // must be an operand
output = output + ch; // write it to output
break;
} // end switch
} // end for
while( !theStack.isEmpty() ) // pop remaining opers
{
theStack.displayStack("While "); // *diagnostic*
output = output + theStack.pop(); // write to output
}
theStack.displayStack("End "); // *diagnostic*
return output; // return postfix
} // end doTrans()
public void gotOper(char opThis, int prec1)
{ // got operator from input
while( !theStack.isEmpty() )
{
char opTop = theStack.pop();
if( opTop == '(' ) // if it's a '('
{
theStack.push(opTop); // restore '('
break;
}
else // it's an operator
{
int prec2; // precedence of new op
if(opTop=='+' || opTop=='-') // find new op prec
prec2 = 1;
else
prec2 = 2;
if(prec2 < prec1) // if prec of new op less
{ // than prec of old
theStack.push(opTop); // save newly-popped op
break;
}
else // prec of new not less
output = output + opTop; // than prec of old
} // end else (it's an operator)
} // end while
theStack.push(opThis); // push new operator
} // end gotOp()
public void gotParen(char ch)
{ // got right paren from input
while( !theStack.isEmpty() )
{
char chx = theStack.pop();
if( chx == '(' ) // if popped '('
break; // we're done
else // if popped operator
output = output + chx; // output it
} // end while
} // end popOps()
} // end class InToPost
class ParsePost
{
private Stacky theStack1;
private String input;
//--------------------------------------------------------------
public ParsePost(String output)
{ input = output; }
//--------------------------------------------------------------
public int doParse(String output)
{
theStack1 = new Stacky(20); // make new stack
char ch;
int j;
int num1, num2; int interAns;
for(j=0; j<input.length(); j++) // for each char,
{
ch = input.charAt(j); // read from input
theStack1.displayStack(""+ch+" "); // *diagnostic*
if(ch >= '0' && ch <= '9') // if it's a number
theStack1.push( ((ch-'0') )); // push it
else // it's an operator
{
num2 = theStack1.pop(); // pop operands
num1 = theStack1.pop();
switch(ch) // do arithmetic
{
case '+':
interAns = num1 + num2;
break;
case '-':
interAns = num1 - num2;
break;
case '*':
interAns = num1 * num2;
break;
case '/':
interAns = num1 / num2;
break;
default:
interAns = 0;
} // end switch
theStack1.push(interAns); // push result
} // end else
} // end for
interAns = theStack1.pop(); // get answer
return interAns;
} // end doParse()
} // end class ParsePost
class lab2
{
public static void main(String[] args) throws IOException
{
String input, output,newout;
while(true)
{
String stuff;
System.out.print("Enter infix: ");
System.out.flush();
input = getString(); // read a string from kbd
if( input.equals("") ) // quit if [Enter]
break;
// make a translator
InToPost theTrans = new InToPost(input);
output = theTrans.doTrans(); // do the translation
System.out.println("Postfix is " + output.toString());
stuff = output.toString();
ParsePost aParser = new ParsePost(input);
output = (aParser.doParse(output)); // do the evaluation
System.out.println("Postfix is " + output);
}
} // end main()
public static String getString() throws IOException
{
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(isr);
String s = br.readLine();
return s;
}
}
