namespace ---> System.Text.RegularExpressions.
static void Main(string[] args)
{
// if (IsInputMatchesNumber())
if (IsInputMatchesNumberByRegx())
{
Console.WriteLine("Input charectors are all numbers.");
}
else
{
Console.WriteLine("Input charectors are not pure numbers.");
}
}
//Common way to judge whether a string is pure numbers or not
static bool IsInputMatchesNumber()
{
Console.Write("Please input your password: ");
string str = Console.ReadLine();
bool isMatch = true;
for (int i = 0; i < str.Length; i++)
{
if (str[i] < '0' || str[i] > '9')
{
isMatch = false;
break;
}
}
return isMatch;
}
//Use regular expressions to judge, result is the same as above
static bool IsInputMatchesNumberByRegx()
{
Console.Write("Please input your password: ");
string str = Console.ReadLine();
//Regular expression always come with @
// @ means "do not convert \ in string"
// ^ means "start from"
// $ means "end at"
// * means "has any"
// \d means "number"
string pattern = @"^\d*$";
return Regex.IsMatch(str, pattern);
}
