Issue in Fortify Null Deference while using substring in C#

Question

We use Fortify to scan the code for our application. In one particular code as shown below

dr["test"] = GetTest(temp.Type!.Substring(0, 1));

Fortify throws null Deference error. So, I changed the code as shown below

dr["test"] = GetTest(temp.Type.Length > 0 ? temp.Type!.Substring(0, 1) : temp.Type);

though I am getting the same Null Deference error. I googled some codes related to null deference but I did not get the exact solution.

Does this answer your question? [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — madreflection, Mar 29 '21 at 18:54

score 1 · Answer 1 · answered Mar 29 '21 at 19:26

1

If the problem is in temp.Type, you could try validating with IsNullOrEmpty. link

answered Mar 29 '21 at 19:26

Juan Ozuna

32
4

ya i have checked with isnullorempty. but it still shows same error – Zia Zee Mar 30 '21 at 07:42

score 0 · Answer 2 · answered Jul 26 '22 at 07:00

This save SubString function might solve your problems:

///<summary>Get a save substring. If length is < 0, the remainder of the string is returned. Never returns NULL.</summary>
    public static string SaveSubStr( this string value, int offset, int length = -1 ) {
        if ( null == value || 0 == length ) return CS.Empty;
        if ( offset < 0 ) offset = 0;
        var l = value.Length;
        if ( 0 == l ) return value;
        if ( offset > l ) return CS.Empty;
        if ( length < 0 || offset + length > l ) length = l - offset;
        if ( length < 0 ) return CS.Empty;
        return value.Substring( offset, length );
    }

Issue in Fortify Null Deference while using substring in C#

2 Answers2