Thread: [HELP]C Programming , Stack conversion from infix to prefix

Code:

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<ctype.h>


#define MAX 50






char output[MAX];
char stack[MAX];
char input[MAX];
char *s,*t;
char ch;
int top;
int l;
int opr;




void initialize(void);
void SetExpression(char*);
int PopFromStack(char);
int priority(char);
void ConvertToPrefix(void);
void ConvertToPostfix(void);
main (void)




{
     initialize();
     printf("\nEnter an expression in infix form:");
     gets(input);
     printf("\nSpecify output expression type,1)Prefix 2)Postfix");
     ch=getch();
     SetExpression(input);
     if(ch=='1')
     {
                strrev(s);
                ConvertToPrefix();
                strrev(output);
                printf("\nThe Prefix expression is:");
                }
                else
                {
                    ConvertToPostfix();
                    printf("\nThe Postfix expression is:");
                    }
                    *(t)=opr;
                    t++;
                    opr=
                    PopFromStack();
                    }          
                PushOnStack((opr);
                PushOnStack((*(s));
                }
     else PushOnStack(*(s));
     s++;
     }
     if(*(s)=='(')
     {
                  opr=PopFromStack();
                  while(opr!=')')
                  {
                  opr=PopFromStack();
                  }
                  s++;
                  }
     }
     while(top!=-1)
     {
                   opr=PopFromStack();
                   *(t)=opr;
                   t++;
     }
     t++;
     }
         char opr;
         while(*(s))
         {
                       if(*(s))==''||*(s)=='\t')
                       {
                       s++;
                       continue;
                       }
                       if(isdigit(*(s))||isalpha(*(s)))
                       {
                       while(isdigit(*(s))||isalpha(*
                       (s)))
                       {
                            *(t)=*(s);
                            s++;
                            t++;
                       }
         }
         if(*(s)=='(')
         {
                      PushOnStack(*(s));
                      s++;
         }
         if(*(s)=='*'||*(s)=='+'||*(s)
         =='/'||*(s)=='%'||*(s)=='-'||*(s)
         =='^')
         {
               if(top!=-1)
               {
                          opr=PopFromStack();
                          while(priority(opr)>=
                          priority(*(s)))
                          {
                                         *(t)=opr;
                                         t++;
                                         opr=
                                         PopFromStack();
                          }
                          PushOnStack(opr);
                          PushOnStack(*(s));
                          }
                          else PushOnStack(*(s));
                          s++;
                          }
                          if(*(s)==')')
                          {
                                       opr=PopFromStack();
                                       while(opr!='(')
                                       {
                                       *(t)=opr;
                                       t++;
                                       opr=PopFromStack();
                          }
                          s++;
                          }
                          while(top!=-1)
                          {
                          opr=PopFromStack();
                          *(t)=opr();
                          t++;
                          }
                          t++;
                          }
                          getch();
                          }

Please help me , with some errors .

http://i44.tinypic.com/11cfx28.png

my output should look like this ..

Enter an expression in infix form: (9+6)/(2*4)^15

Specify output epression type,1) Prefix 2)Postfix
The Prefix expression is: /+96^*2415

----------------------------------------------

Enter an expression in infix form: (9+6)/(2*4)^15

Specify output epression type,1) Prefix 2)Postfix
The Postfix expression is:96+24*15^/