Detect Leading Zero in String

Question

I'm currently trying to detect if a number has a leading zero. Not sure what the best way is to detect that. An example would something like this "000445454"

Answer 1

Use String.StartsWith

"Determines whether the beginning of this string instance matches a specified string."

string numbers =  "000445454";
if (numbers.StartsWith("0"))
    //Do Something

Answer 2

One easy way to detect a leading zero in a non empty "s" string is to compare its first element with the character '0':

s[0] == '0'

Answer 3

string str = "0";
if(str.StartsWith("0") && str.Length !=1) Console.WriteLine("false");
else Console.WriteLine("true");

if the string starts with '0' and if it has more than one character.

Answer 4

I am not familiar with c# syntax

But in C++ in order to find 00, 05, 01 , i tend to do this:

We can find the index of first zero from left using

index = str.find('0');

And now check if index == 0 means leading ZERO and the length of string is greater than 1

if(index ==0 and str.length()>1){
    cout<<"Leading Zero";
}