一、简介
1.1 介绍
utstack.h中包含了一组动态stack宏。使用起来非常简单，只需要将utstack.h拷贝到你的项目，并包含进你的源码即可：
#include "utstack.h"
utstack.h宏支持栈的基本的操作：push、pop、count，以及获取顶部元素操作。其内部实现为连接的链表。
1.2 源码获取
utlist.h的源码可以在GitHub上直接获取(src/utstack.h)：
https://github.com/troydhanson/uthash
二、使用方法
2.1 栈头声明
栈头是一个结构体指针，指向你自己定义的结构体，注意必须初始化为NULL：
element *stack = NULL
2.2 栈操作
栈的操作只有O(1)的push，O(1)的pop和O(n)的count方法。
为了保证你代码的可读性，你可以使用STACK_EMPTY(head)替代head == NULL，使用STACK_TOP(head)替代head。
| Operations |
description |
| STACK_PUSH(stack,add); |
push add onto stack |
| STACK_POP(stack,elt); |
pop stack and save previous top as elt |
| STACK_COUNT(stack,tmp,count); |
store number of elements into count |
| STACK_TOP(stack) |
return stack |
| STACK_EMPTY(stack) |
return stack == NULL |
表格中用到的参数说明如下：
- stack：The stack head (a pointer to your element structure).
- add：A pointer to the element structure you are adding to the stack.
- elt：A pointer that will be assigned the address of the popped element. Need not be initialized.
- tmp：A pointer of the same type as elt. Used internally. Need not be initialized.
- count：An integer that will be assigned the size of the stack. Need not be initialized.
2.3 一个简单的实例
下面的实例读取文件内容，然后push每行到stack，然后pop取出数据后打印出来。
/* A stack of names*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "utstack.h"
#define BUFLEN 20
typedef struct el {
char bname[BUFLEN];
struct el *next;
} el;
el *head = NULL; /* important- initialize to NULL! */
int main(int argc, char *argv[]) {
el *elt;
char linebuf[BUFLEN];
int count;
FILE *file = fopen("test11.dat", "r");
if (file == NULL) {
perror("can't open: ");
exit(-1);
}
while (fgets(linebuf, sizeof linebuf, file) != NULL) {
el *name = malloc(sizeof *name);
if (name == NULL) exit(-1);
strcpy(name->bname, linebuf);
STACK_PUSH(head, name);
}
fclose(file);
STACK_COUNT(head, elt, count);
printf("%d elements were read into the stack\n", count);
/* now pop, print, and delete each element */
while (!STACK_EMPTY(head)) {
printf("%s\n", STACK_TOP(head)->bname);
STACK_POP(head, elt);
free(elt);
}
return 0;
}
2.4 其他宏
当你的结构体的next字段命名不是next，那么你可能会用到如下宏：
| Operations |
description |
| STACK_PUSH2(stack,add,next); |
push add onto stack |
| STACK_POP2(stack,elt,next); |
pop stack and save previous top as elt |
| STACK_COUNT2(stack,tmp,count,next); |
store number of elements into count |
