[TOC]
### 定義
### ADT
### 代碼實現
```
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
struct elt {
struct elt *next;
int value;
};
struct queue {
struct elt *head;
struct elt *tail;
};
typedef struct queue *q;
struct queue *
queueCreate(void) {
struct queue *q;
q = malloc(sizeof(* q));
q->head = q->tail = 0;
return q;
}
void
enq(struct queue *q,int value){
struct elt *e;
e = malloc(sizeof(* e));
assert(e);
e->value = value;
e->next = 0;
if(q->head == 0) {
q->head = e;
}
else {
q->tail->next = e;
}
q->tail = e;
}
int
queueEmpty(const struct queue *q) {
return (q->head == 0);
}
int
deq(struct queue *q) {
int ret;
struct elt *e;
assert(!queueEmpty(q));
ret = q->head->value;
e = q->head;
q->head = e->next;
free(e);
return ret;
}
void
queuePrint(struct queue *q) {
struct elt *e;
for(e=q->head;e!=0;e=e->next) {
printf("%d ",e->value);
}
putchar('\n');
}
void
queueDestroy(struct queue *q) {
while(!queueEmpty(q)) {
deq(q);
}
free(q);
}
int
main(int argc,char **argv) {
int i;
struct queue *q;
q = queueCreate();
for(i=0;i<5;i++) {
printf("enq %d\n",i);
enq(q,i);
queuePrint(q);
}
while(!queueEmpty(q)) {
printf("deq gets %d\n",deq(q));
queuePrint(q);
}
queueDestroy(q);
return 0;
}
```
