C# 如何在代码中添加约束
本文关键字：添加 约束 代码 | 更新日期: 2023-09-27 18:35:42
我编写了以下代码，根据用户的年龄计算公园入场费总额。代码运行良好。我想再添加一个功能，如果用户输入年龄值<0;再给用户 2 次机会输入正确的年龄值（年龄值必须为>= 0）。尝试 3 次后会出现错误消息 Invalid...，程序将打印"谢谢"并终止。我不需要有人写代码，我需要知道我可以在哪里以及如何在我的代码中实现此功能。
静态空 主（字符串[] 参数） {
string username;
int password, count=0 , num_guest , age;
for (int i = 0; i < 3; i++)
{
Console.Write("Username : ");
username = Console.ReadLine().ToString();
Console.Write("Password : ");
password = Convert.ToInt32(Console.ReadLine());
if (password.Equals(63100))
{
Console.Clear();
Console.WriteLine("Welcome " + username);
Console.Write("Enter number of guests : ");
num_guest = Convert.ToInt32(Console.ReadLine());
if (num_guest <= 0)
{
Console.Clear();
Console.WriteLine("Thank You");
Environment.Exit(0);
}
else
{
for (int j = 1; j <num_guest+1; j++)
{
Console.Write("Enter age of "+j+" guest : ");
age = Convert.ToInt32(Console.ReadLine());
if (age >= 0)
{
if (age == 0 && age == 1)
{
count = count + 0;
}
else if (age >= 2 && age <= 17)
{
count = count + 60;
}
else if (age >= 18 && age <= 59)
{
count = count + 35;
}
else if (age > 60)
{
count = count + 30;
}
}
}
Console.WriteLine(count);
Console.ReadLine();
}
break;
}
else
{
Console.WriteLine("Incorrect Password!");
}
}
Console.Clear();
Console.WriteLine("Bye..." );
Environment.Exit(0);
}
您应该将
循环与计数器一起使用，每次age <= 0时递增计数器。在循环开始时，检查计数器是否为 3，然后打印错误消息并退出。
否则，如果一切正常，请从while循环中break;。
int counter = 0;
while (true)
{
if (counter == 3) {
Console.WriteLine("Thank You");
Environment.Exit(0);
}
age = Convert.ToInt32(Console.ReadLine());
if (age > 0)
break;
counter++;
}
将
while 循环与计数器一起使用，当它达到 0 时终止或中断 当用户输入有效年龄时终止或中断
static void Main(string[] args)
{
string username;
int password, count=0 , num_guest , age;
for (int i = 0; i < 3; i++)
{
Console.Write("Username : ");
username = Console.ReadLine().ToString();
Console.Write("Password : ");
password = Convert.ToInt32(Console.ReadLine());
if (password.Equals(63100))
{
Console.Clear();
Console.WriteLine("Welcome " + username);
Console.Write("Enter number of guests : ");
num_guest = Convert.ToInt32(Console.ReadLine());
if (num_guest <= 0)
{
Console.Clear();
Console.WriteLine("Thank You");
Environment.Exit(0);
}
else
{
//make counter here
for (int j = 1; j <num_guest+1; j++)
{
Console.Write("Enter age of "+j+" guest : ");
age = Convert.ToInt32(Console.ReadLine());
if (age >= 0)
{
//reset counter here
if (age == 0 && age == 1)
{
count = count + 0;
}
else if (age >= 2 && age <= 17)
{
count = count + 60;
}
else if (age >= 18 && age <= 59)
{
count = count + 35;
}
else if (age > 60)
{
count = count + 30;
}
}
else
{
// minus 1 of j increment counter here if counter hits 3 then ouput message then terminate program
}
}
Console.WriteLine(count);
Console.ReadLine();
}
break;
}
else
{
Console.WriteLine("Incorrect Password!");
}
}
Console.Clear();
Console.WriteLine("Bye..." );
Environment.Exit(0);
}
读取并解析年龄输入后，可以使用 while 循环对其进行验证，如果无效，请再次请求它。
Console.Write("Enter age of "+j+" guest : ");
age = Convert.ToInt32(Console.ReadLine());
int tries = 0;
while (age < 0)
{
if (tries >= MAX_TRIES)
return;
else
++tries;
Console.WriteLine("Age must be zero or a positive number");
age = Convert.ToInt32(Console.ReadLine());
}
首先，
您应该开始将代码分解为单独的方法以提高可读性。一个可以命名为 ReadValidAge，如果用户在 3 次尝试中未输入有效年龄，则返回 -1。像这样：
private static int ReadValidAge(int guestNumber)
{
int result;
for(int i = 3; i > 0;)
{
Console.Write("Enter Age of guest {0}: ", guestNumber);
if(int.TryParse(Console.ReadLine(),out result) && result > 0)
{
return result;
}
else
{
Console.WriteLine("Invalid Age entered ... {0} Tries left!", --i);
}
}
return -1;
}
然后你调用它并使用 if 语句分支到程序之外：
for (int j = 1; j <num_guest+1; j++)
{
age = ReadValidAge(j);
if(age == -1)
{
//Say byebye here
return;
}
// your orignal code