Implementing generic stack

[puneetsardana88]

Hi

Currently I am implementing a generic(int plus float etc) stack in C. However I am facing some problems.

stackgen.h

#define STACKSIZE 100
#define INTEGER 1
#define FLOAT 2
#define STRING 3
struct stackelement
 {
     int etype;
     union
      {
          int i;
          float f;
      }element;
 };
struct stack
 {
     int top;
     struct stackelement items[STACKSIZE];
 };
void init(struct stack *);
void printtop(struct stack *);
void push(struct stack *,int,void);

stackgen.c

#include "stackgen.h"
void init(struct stack *mycopy)
 {
     mycopy->top=-1;
 }
void printtop(struct stack *mycopy)
 {
     struct stackelement se;
     se=mycopy->items[mycopy->top];
     //printf("%d",se.etype);
     switch(se.etype)
      {
          case INTEGER:
            printf("%d\n",se.element.i);
            break;
          case FLOAT:
            printf("%f\n",se.element.f);
            break;
      }
 }
void push(struct stack *mycopy,int etype,void *item)
 {
     int *intptr;
     float *floatptr;
     (mycopy->top)++;
     mycopy->items[mycopy->top].etype=etype;
     switch(etype)
      {
          case INTEGER:

            intptr=(int *)item;
            (mycopy->items[mycopy->top].element.i)=*intptr;
            break;

          case FLOAT:
             floatptr=(float *)item;
             (mycopy->items[mycopy->top].element.f)=*floatptr;
             break;
      }

 }
int main()
 {
     struct stack my;
     init(&my);

     int i=100;
     float f=23.23;
     push(&my,1,&i);
     push(&my,2,&f);
     printtop(&my);
     return 0;
 }

The above code works absolutely fine. But what i need is the functionality that user enter either int or float at run time and push gets called accordingly. I do not want to ask from the user whether next input he will enter would be an int or float? How can I accomplish this?

[donbock]

When you say "I do not want to ask from the user whether next input he will enter would be an int or float" do you mean that the user will interactively type in values to be pushed onto the stack? If so, then your user input should be entered as a string that your program will parse into one of three categories: int, float, or invalid.

The Standard Library functions strtol and strtod can do the heavy lifting for you.

[puneetsardana88]

Thank You Donbock. I think I need to make my own function that will check the string for integer float or character.