Urgent!!: Convert a char to a double.

Hello Experts,

I was wondering if there is a built-in function that I could use to convert a 'char' to
a 'double' without loosing the initial values. Yes! It's HomeWork. I just need some pointers. This program takes in a postscript expression and changes it back to infix. I am getting stuck because the data was inputed as 'char' and I need it to be 'double'. I tried 'strtod' but it didn't work.


Newbie Code below .....hehe
----------------------------------------
#include <iostream>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <cstdlib>
#include <cstring>

using namespace std;
const int MAX = 8;
double array[MAX];
bool isempty(int);
int pop(void);
int push(double x);
bool isfull(int num);
bool isnumber(char num);
int validate(char p1, int, int);
void evaluate(char postfix[]);
int packStack(char getData[], int length);


/*********************************************************************************************
**                                                            FUNCTION MAIN  : ........



**********************************************************************************************/


int main()
{
      int num = -1;
      int tos = -1;
      double answer = 0;
      char array2[20];
      char * p1 = NULL;
      p1 = array2;
      cout<<"Enter your expression"<<endl;
      cin.getline(array2,20,'\n');
      int length = strlen(array2);
      for(int j = 0; j < length; j++)
      {
            array[j] = array2[j];
            if(array2[j] == ' ')
                  continue;
            cout<<"HERE: "<<array2[j]<<endl;
            
      }
      answer = packStack(array2,length);
      
      cout<<"THE ANSWER: "<<answer<<endl;
      return 0;
      
}

/*********************************************************************************************
          FUNCTION DECLARATIONS : PUSH, POP, ISEMPTY, ISFULL, TOS, VALIDATE, SP........



**********************************************************************************************/


bool isempty(int num)
{
      if(num == -1)
            return true;
      else
            return false;
}

bool isfull(int num)
{
      int max = 10;
      if(num == max - 1)
            return true;
      else
            return false;
}

int pop(void)
{
      int num = 5;
      if(isempty(num) == 1)
      {
            cout<<"ERROR: Stack UnderFlow\n";
      }
      else
      {
            array[num--];
      }
      return array[num];      
}

int push(double x)
{
      int num = 5;
      char *p1;
      
      char mim = array[0];
      double test;
      //test = (strtod(mim,&p1));
      
      if(isfull(num) == 1)
      {
            cout<<"ERROR: Stack OverFlow\n";
      }
      else
      {
            array[num++] = x;
      }
      return array[num];
}

bool isnumber(char num)
{
      return isdigit(num);
}

int validate(char p1, int ops, int nums)
{
      char mul = '*';
      char div = '/';
      char min = '-';
      char pows = '$';
      char plus = '+';
      
            if(p1 == mul)
                  return 6;
            if(p1 == 'min')
                  return 5;
            if(p1 == div)
                  return 4;
            if(p1 == plus)
                  return 3;
            if(p1 == pows)
                  return 2;
            else
                  return 1;

            return 0;
}
      
int packStack(char getData[], int length)
{
      char *numbers = new char [length];
      char *operators = new char[length];
      char *infix = new char[length];
      char *postfix = new char[length];
      int opcount = 0;
      int numcount = 0;
      for(int j = 0; j < length; j++)
      {
            postfix[j] = getData[j];
            if(isnumber(getData[j])==1)
            {
                  numbers[j] = getData[j];
                  numcount++;
            }
            if(isnumber(getData[j])==0)
            {
                  operators[j] = getData[j];
                  opcount++;
                  cout<<endl;
            }
      }
      char temp;
      for(int k = 0; k < length; k++)
      {
            
            temp = getData[k];
            int ret = 0;
            ret = validate(temp,opcount,numcount);
            if (ret == 6)
            {
                  cout<<"Multiply";
                  double temp2 = 0;
                  temp2 = pop();
                  push(pop() * temp2);
            }
            if(ret == 3)
            {
                  cout<<"ADD"<<endl;
                  int temp2 = pop();
                  push(pop() + temp2);
            }
      }
      return 0;                               
}