How can I compare part of a string?

In .NetCore, or .Net framework with System.Memory nuget package:

str1.Length >= 5 && str2.Length >= 5 && str1.AsSpan(0, 5).SequenceEqual(str2.AsSpan(0, 5))

This is extremely heavily optimized, and will be the best performing of all the options here.

If your strings are at least 5 characters long, then string.Compare should work:

var match = string.Compare(str1, 0, str2, 0, 5) == 0;

bool startsWithFoo = "foobar".StartsWith( "foo" );

Try this:

if (str1.Lenght >= 5 && 
    str2.StartsWith(str1.Substring(0, 5)))
{
    // Do what you please
}

Related