stack

stack.c

#include <stdio.h>
#include <stdlib.h>

static int sz = 512;
static char *stack;//数据栈
static int top = 0;
void init_stack(int size)
{
    if(size == 0)
        size = sz;
    else
        sz = size;
    stack =(char *)malloc(sz);
}
void destory_stack(void)
{
    free(stack);
}
void push(char ch)
{
    if(top == sz)
    {
        sz += sz;
        stack = (char *)realloc(stack, sz);
    }
    stack[top++] = ch;
}
char pop(void)
{
    return stack[--top];
}
int is_empty(void)
{
    return top == 0;
}
int is_full(void)
{
    return top == sz;
}

stack.h

extern void push(char ch);
extern char pop(void);
extern int is_empty(void);
extern int is_full(void);
extern void init_stack(int size);
extern void destory_stack(void);

stack_main.c

#include <stdio.h>
#include "stack.h"
int main(void)
{
    char *str = "abcdefghijklmn";
    init_stack(3);
    while(*str != '\0'){
        push(*str);
        str++;
    }
    while(is_empty() == 0 )
        putchar(pop());
    putchar('\n');
    destory_stack();
    return 0;
}