这份代码是在之前介绍的互斥锁的代码上直接改过来的，可以对比看看
account.h:
#ifndef __ACCOUNT_H__
#define __ACCOUNT_H__
#include <pthread.h>
#include <semaphore.h>
typedef struct
{
int code;
double balance;
sem_t sem;
}Account;
extern Account * create_account(int code,double balance);
extern void destroy_account(Account *a);
extern double with_draw(Account *a,double amt);
extern double depoist(Account *a,double amt);
extern double get_balance(Account *a);
#endif
account.c:
#include "account.h"
#include <assert.h>
#include <malloc.h>
#include <string.h>
Account *create_account(int code, double balance)
{
Account *r=(Account *)malloc(sizeof(Account));
assert(r!=NULL);
r->code=code;
r->balance=balance;
sem_init(&r->sem,0,1);
return r;
}
void destroy_account(Account *a)
{
assert(a!=NULL);
sem_destroy(&a->sem);
free(a);
}
double with_draw(Account *a, double amt)
{
assert(a!=NULL);
sem_wait(&a->sem);
if(amt > a->balance || amt<0){
sem_post(&a->sem);
return 0.0;
}
double balance=a->balance;
sleep(1);
balance = balance - amt;
sleep(1);
balance = balance - amt;
a->balance = balance;
sem_post(&a->sem);
return amt;
}
double depoist(Account *a, double amt)
{
assert(a!=NULL);
if(amt<0){
return 0.0;
}
sem_wait(&a->sem);
double balance=a->balance;
sleep(1);
balance = balance + amt;
a->balance = balance;
sem_post(&a->sem);
return amt;
}
double get_balance(Account *a){
sem_wait(&a->sem);
double balance = 0.0;
balance=a->balance;
sem_post(&a->sem);
return balance;
}
test.c:
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "account.h"
typedef struct
{
char name[20];
Account *account;
double amt;
}Arg;
void *func_th(void *arg)
{
Arg *r=(Arg *)arg;
double amt=with_draw(r->account,r->amt);
printf("%8s(0x%lx) withdraw %f from account %d\n",
r->name,pthread_self(),amt,r->account->code);
return (void*)0;
}
int main(int argc,char *argv[])
{
int err;
pthread_t boy,girl;
Account *a=create_account(1001,10000);
Arg r1,r2;
strcpy(r1.name,"man");
r1.account=a;
r1.amt=10000;
strcpy(r2.name,"woman");
r2.account=a;
r2.amt=10000;
if((err=pthread_create(&boy,NULL,func_th,(void *)&r1))!=0)
{
perror("pthread create error");
}
if((err=pthread_create(&girl,NULL,func_th,(void *)&r2))!=0)
{
perror("pthread create error");
}
pthread_join(boy,NULL);
pthread_join(girl,NULL);
//打印余额
printf("the rest of the count is %f\n",get_balance(a));
//打印线程ID
printf("%lx thread finished\n",pthread_self());
return 0;
}