A letter that efficiently determines whether a string is fully digital

String

See a lot of people using regular expressions or some other different kinds of algorithms. After a simple test, the following wording should be more efficient.

public static bool Isnum (String str)
{
for (int i=0;i<str. length;i++)
{
if (str[i]<= ' 0 ' | | | str[i]>= ' 9 ')
return false;
}
return true;
}

Finally, attach the relevant regular expression to the validation reference regular expression: "^\d+$"

In addition, if someone likes to use Char.isnumber (), but the method has the advantage of compatible with the full angle, so the overall speed is not particularly good.