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[英]I want make all textboxes on my form to accept only numbers with as little code as possible - c#
[英]Can I make my code not accept any input other than an int C#
我希望我的代码只接受 integer。 我认为通过在 int 范围内放置 if else 语句会对此有所帮助,但是当输入文本作为输入时,它只会使程序崩溃。 我怎样才能解决这个问题。
using System;
namespace planetage
{
class Program
{
static void Main(string[] args)
{
const double mercuryYears = 0.24;
Console.WriteLine("Please enter your age"); //Ask for users age
int userAge = Convert.ToInt32(Console.ReadLine()); //take users age and convert to int from string
if (userAge >= 0 && userAge <= 150) {
double mercuryAge = userAge / mercuryYears; //calculation for age on mercury
Console.WriteLine("Your age on Mercury is " + mercuryAge); //output age on mercury
} else
{
Console.WriteLine("Please enter your age");
}
}
}
}
如果您查看Convert.ToInt32(string)
的文档,您将看到在以下条件下引发了异常:
FormatException
值不包含可选符号后跟数字序列(0 到 9)。
如果您想不断地要求一个有效的 integer 直到给出一个,您可以使用以下方法:
int userAge;
do Console.WriteLine("Please enter your age");
while (int.TryParse(Console.ReadLine(), out userAge) is false);
// Do something with userAge..
仅当string
已成功转换为int
时, int.TryParse
返回true
,并且不会引发任何异常。
这应该这样做
Console.WriteLine("Please enter your age"); //Ask for users age
int userAge;
while (!int.TryParse(Console.ReadLine(), out userAge)) {
Console.WriteLine("Not a valid number");
}
if (userAge >= 0 && userAge <= 150)
{
double mercuryAge = userAge / mercuryYears; //calculation for age on mercury
Console.WriteLine("Your age on Mercury is " + mercuryAge); //output age on mercury
}
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