解释下面代码含义 typedef struct { double balance; } bankaccount; //开户 void openaccount(bankaccount *account) { account->balance = 0; printf("开户成功"); } //存款 void deposit(bankaccount *account, double amount) { account->balance += amount; printf("\n") ; printf("存款 %.2f 成功", amount); } //取款 void withdraw(bankaccount *account, double amount) { if (account->balance >= amount) { account->balance -= amount; printf("\n") ; printf("取款 %.2f 成功", amount); } else { printf("\n") ; printf("取款 %.2f，余额不足失败", amo