Thread: Array Stack Problem

Here is what I am trying to do:
I am inputting this file with this expression: XYZ+A*B/+CX*-
I already have a character arrays with these entered into it:
A=2
B=10
C=5
X=8
Y=6
Z=4
When I input a character it's corresponding number goes on the stack
and then when I come to a operator I pop the two numbers from the
stack and add them if the operator is + or multiply if the operator is
a *, or subtract if the operator is a -, or divide it the operator
is a /. The sum is just applied to the next mathmatical operation.

The alogorithm should go like this:
while(Infile)
if (inputchar == alphabet)
got to the table array
find the match on the table arrya
Then pust the value to the stack
else if(inputchar == operators)
go to stack
pop out two items
then apply the operators
the output result should be pushed to the stack

I get a output of 2 when I should get a output of -30. I ran the debugger
and at this line inFile2>>cInpChar; I am getting 44 ',' and at this line if(inFile2.eof()){
I am getting 88 'x'.
I can't understand why I am getting those values for my input number when
it should be inputting the value that is stored in the array. My header
and implementation file are correct.

[ccode]
#include<iostream.h>
#include<fstream>

#include<iomanip>
#include"cs.cpp"
using namespace std;

int main()
{

// Data Arrays
numberstack os;
const int CNUM_MaxCnt= 50;
const int CNUM_MaxVarNameLen= 32;

char szVarName[CNUM_MaxCnt][CNUM_MaxVarNameLen];
char szEqualSign[CNUM_MaxCnt][2];
int nVarVal[CNUM_MaxCnt];
int Topitem;
int firstitem = 0;

ifstream inFile; inFile.open( "input1.txt");
ofstream outFile; outFile.open("output3.txt");
ifstream inFile2; inFile2.open( "input2.txt");
//ofstream outFile2; outFile.open("output3.txt");
// X+(Y+Z)*A/B-C*X:A=2,B=10,C=5,X=8,Y=6,Z=4

char cInpChar;
while( !inFile.eof() ) {
inFile >> cInpChar;
if ( cInpChar == ':') {
break; // all done
}
outFile << cInpChar;
}
outFile.close();
// now at A=2,B=10,C=5,X=8,Y=6,Z=4
int nCur= 0;
while( !inFile.eof() ) {
inFile.get( szVarName[nCur],CNUM_MaxVarNameLen,'=');

inFile >> szEqualSign[nCur][0]; // get the = sign
szEqualSign[nCur][1]= '\0'; // terminate the strung

inFile >> nVarVal[nCur]; // read an int from the stream
inFile >> cInpChar; // skip the comma

nCur++;
}
for (int j=0; j< nCur; j++ ) {
cout << szVarName[j] << szEqualSign[j] << nVarVal[j] << endl;
}
int nResult = 0;
int sum = 0;
int nVal = 0;

while(true){
inFile2>>cInpChar;

if(inFile2.eof()){
break;
}
bool fVarFound=false;
for(int i = 0; i < CNUM_MaxCnt; i++)
{
if(szVarName[i][0]=cInpChar)
{
nVal=nVarVal[i];
fVarFound = true;
break;
}
if(szVarName[i][0]==0){
break;
}
}
if(fVarFound){
os.Push(nVal);
continue;
}
if(cInpChar=='+'||cInpChar=='-'||cInpChar=='*'||cInpChar=='/')
{
int nValTop=os.top(); os.pop();
int nValNxt=os.top(); os.pop();
int nResult = 0;
switch(cInpChar)
{
case '+': nResult=nValTop+nValNxt;
break;
case '-': nResult=nValNxt-nValTop;
break;
case '*': nResult=nValTop*nValNxt;
break;
case '/': nResult=nValNxt/nValTop;
break;
}

os.Push(nResult);

}

else
{
cout<<"Invalid variable"<<endl;
exit(1);
}

}

int nFinal=os.top();
os.pop();

cout<<nFinal<<endl;


return(0);
}

#include<iostream.h>
#include<iomanip>

#include"cs.h"
numberstack::numberstack()
{
TopIndex = -1;
}

//--------------------------------------------------------------------
//Function to check if the stack is empty.
bool numberstack::Isstackempty() const
{
return (TopIndex == -1);
}
//--------------------------------------------------------------------
//Function to check if the stack is full.
bool numberstack::Isstackfull() const
{
return (TopIndex == NumberArray - 1);
}
//--------------------------------------------------------------------
//Push function to push the characters and operators on the stack.
void numberstack::Push(int a)
{
if( !Isstackfull() )
arr[++TopIndex] = a;
else
{
cout<<"Stack is full." << endl;
exit(1);
}
}
//Returns top element/
//--------------------------------------------------------------------
char numberstack::top() const
{
return arr[TopIndex];

}
//--------------------------------------------------------------------
//Pop function to pop the characters and operators on the stack.
void numberstack:op()
{
/*char result=arr[TopIndex];*/
if( !Isstackempty() )
TopIndex--;
else
{
cout<<"Stack is empty.";
exit(1);
}
//return result;
}

//Global variable to set the array to 26
const int NumberArray = 26;

//Class Structure
class numberstack
{
//Public functions in the class and the constructure.
public:


bool Isstackempty() const;
bool Isstackfull() const;

void Push(int a);
char top() const;
void pop();

numberstack();
//Private variables in the class stack.
private:
int TopIndex;
int arr[NumberArray];



};

Just one little typo. You need an == instead of an = (see below).

Code:

int nResult = 0; 
int sum = 0;
int nVal = 0; 

while(true){ 
   inFile2>>cInpChar; 

   if(inFile2.eof()){ 
      break; 
   } 
   bool fVarFound=false; 
   for(int i = 0; i < CNUM_MaxCnt; i++) 
   { 
      if(szVarName[i][0]==cInpChar)  //CHANGE THIS
      { 
         nVal=nVarVal[i]; 
         fVarFound = true; 
         break; 
      } 
      if(szVarName[i][0]==0){ 
         break; 
      } 
}

Your code does give the correct answer of -30.

Man!!! Thanks!!! How could I have missed that