#include <stdio.h>
#include <string.h>
#include "Item.h"
#include "STACK.h"
main(int argc, char *argv[])
  { char *a = argv[1]; int i, N = strlen(a);
    STACKinit(N);
    for (i = 0; i < N; i++)
      {
        if (a[i] == ')')
          printf("%c ", STACKpop());
        if ((a[i] == '+') || (a[i] == '*'))
          STACKpush(a[i]);
        if ((a[i] >= '0') && (a[i] <= '9'))
          printf("%c ", a[i]);
      }
    return 0;
    printf("\n");
  }

for STACK.h:

void STACKinit(int);
int STACKempty();
void STACKpush(Item);
Item STACKpop();

for Item.h

typedef char* Item;
#define eq(A,B) strcmp(A,B)==0)

for STACK.c:

#include <stdlib.h>
#include "Item.h"
#include "STACK.h"
static Item *s;
static int N;
void STACKinit(int maxN)
  { s = malloc(maxN*sizeof(Item)); N = 0; }
int STACKempty()
  { return N == 0; }
void STACKpush(Item item)
  { s[N++] = item; }
Item STACKpop()
  { return s[--N]; }

for Makefile:

CC=gcc
CFLAGS=-g -W -Wall -I.
HEADERS=STACK.h Item.h
OBJECTS=inftopost.o STACK.o

PROGNAME=inftopost

$(PROGNAME): $(OBJECTS)
    $(CC) $(CFLAGS) $(OBJECTS) -o $(PROGNAME)

inftopost.o: inftopost.c $(HEADERS)
    $(CC) -c $(CFLAGS) inftopost.c -o inftopost.o

STACK.o: STACK.c $(HEADERS)
    $(CC) $(CFLAGS) $(OBJECTS) -o STACK.o


.PHONY: clean ctags

tags: ctags


ctags:
    ctags -R

clean:
    rm -rf $(OBJECTS) $(PROGNAME)

string Utility::InfixToPostfixOperation(string& strInput)
{
    vector<string> strvInput;         //vector to hold the referenced Split(strInput)
    stack<char> cStack;                 //stack of characters (Operators)
    char cStackToPostfix = ' ';         //character to add(pop) to postfix result
    string strPostfixResult = " ";   //string to hold postfix notation result
    int nSize = strvInput.size();     //length of the infix notation expression
    vector<string>::iterator Itv;     //vector Iterator
    
    strvInput = Split(strInput);

    for(Itv = strvInput.begin(); Itv != strvInput.end(); Itv++)
    {
        string strTemp =* Itv;
        if(strTemp == "*" || strTemp == "/" || strTemp == "+" || strTemp == "-" || strTemp == "=" || strTemp == "(" || strTemp == ")")
        {
            if(strTemp == "=")
            {
                cStack.push('=');
            }//end if
            else if(strTemp == "-" && !cStack.empty())
            {
                if(cStack.top() == '=' || cStack.top() == '*' || cStack.top() == '/' || cStack.top() == '+' || cStack.top() == ')' || cStack.top() == '(')
                {
                    if(cStack.top() == '(')
                    {
                        cStack.push('-');
                    }
                    else if(cStack.top() == '*' || cStack.top() == '/' || cStack.top() == '+')
                    {
                        strPostfixResult += " ";
                        strPostfixResult += cStack.top();
                        cStack.pop();
                        cStack.push('-');
                    }
                    else
                    {
                        cStack.push('-');
                    }
                }//end while
            }//end else if
            else if(strTemp == "+" && !cStack.empty())
            {
                if(cStack.top() == '=' || cStack.top() == '*' || cStack.top() == '/' || cStack.top() == '(' || cStack.top() == '(')
                {
                    if(cStack.top() == '(')
                    {
                        cStack.push('+');
                    }
                    else if(cStack.top() == '*' || cStack.top() == '/')
                    {
                        strPostfixResult += " ";
                        strPostfixResult += cStack.top();
                        cStack.pop();
                        cStack.push('+');
                    }
                    else
                    {
                        cStack.push('+');
                    }
                }//end while
            }//end else if
            else if(strTemp == "/" && !cStack.empty())
            {
                if(cStack.top() == '+' || cStack.top() == '-' || cStack.top() == '=' || cStack.top() == '*' || cStack.top() == '(' || cStack.top() == ')')
                {
                    if(cStack.top() == '(')
                    {
                        cStack.push('/');
                    }
                    else if(cStack.top() == '*')
                    {
                        strPostfixResult += " ";
                        strPostfixResult += cStack.top();
                        cStack.pop();
                        cStack.push('/');
                    }
                    else
                    {
                        cStack.push('/');
                    }
                }
            }//end else if
            else if(strTemp == "*" && !cStack.empty())
            {
                if(cStack.top() == '/' || cStack.top() == '+' || cStack.top() == '-' || cStack.top()== '=' || cStack.top() == '(' || cStack.top() == ')')
                {
                    cStack.push('*');
                }
            }//end else if
            else if(strTemp == "(")
            {
                cStack.push('(');
            }
            else if(strTemp == ")")
            {
                while(!cStack.empty() && cStack.top() != '(')
                {
                    strPostfixResult += " ";
                    strPostfixResult += cStack.top();
                    strPostfixResult += " ";
                    cStack.pop();
                }
                if(!cStack.empty())
                {
                    cStack.pop();
                }
            }
        }//end if
        if(strTemp != "*" && strTemp != "/" && strTemp != "+" && strTemp != "-" && strTemp != "=" && strTemp != "(" && strTemp != ")")
        {
            strPostfixResult += " ";
            strPostfixResult += strTemp;
        }//end if
    }//end for
    while(!cStack.empty())
    {
        if(cStack.top() == '(' || cStack.top() == ')')
        {
            cout << "Invalid Infix Notation Expression... Parantheses Mismatch";
            if(cStack.top() == '(')
            {
                cout << "\nMissing Right Parantheses" << endl << endl;
                cout << "\nAttempted ";
            }//end if
            else if(cStack.top() == ')')
            {
                cout << " \nMissing Left Parantheses" << endl << endl;
                cout << "\nAttempted ";
            }//end else if
        }//end if
        if(cStack.top() == '(' || cStack.top() == ')')
        {
            cStack.pop();
        }//end if
        strPostfixResult += " ";
        strPostfixResult += cStack.top();
        strPostfixResult += " ";
        cStack.pop();
    }
    return strPostfixResult;
}//end InfixToPostfix

vector<string> Utility::Split(const string &strInput, const string &strDelims)
{

    string strTokens;
    vector<string> parsedString;
    string strTemp = strInput;

    int nCol = 0;
    
    while(!strTemp.empty())
    {
        StripBoth(strTemp);
        StripBoth(strTemp, '\t');
        nCol = (int)strTemp.find_first_of(strDelims); //find the position of the first delimiter

        if(nCol == string::npos) //if a delimiter is NOT found
        {
             strTokens = strTemp; //set string to Token (can't parse it so send it back)
             strTemp = "";          //set the remaining string to nothing
        }//END if
        else if(nCol != string::npos) //if a delimiter IS found
        {
            if(nCol == 0)
            {
                nCol = 1;
            }//end if
            strTokens = strTemp.substr(0,nCol); //set strTemp to the string from 0 to the position of the 1st delimiter
            //strTemp = strTemp.substr(nCol+1); //set strTemp to the remaining string
            strTemp = strTemp.substr(nCol);
        }//END else
        parsedString.push_back(strTokens); //put token in vector
    }//END while
    return parsedString;
}//END split