如何验证字符串是否包含 1 个数字 c# [暂停]

Question

So I'm wondering how do I check if a string contains only 1 number?

For example "hello1" would output true but "hello123" would output false because it has more than 1 number.

Please explain it in the most basic way possible, Thanks!

Answer 1

Using Linq, you could do string.Count(x => Char.IsDigit(x)) and check if it's exactly 1.

Answer 2

A simple approach is:

bool HasOnlyOneDigit(string input)
{   
    bool hasDigit = false;
    foreach (char l in input) {
        if (char.IsDigit(l))
        {
            if (hasDigit)
                return false;
            else
                hasDigit = true;
        }
    }
    return hasDigit;
}

In opposition to LINQ, this doesn't require to count the whole string. After finding the second digit it will stop.