API

ToString() should never return `null`

Docs > Code Analysis > Static Analysis Rules > ToString() should never return `null`

Metadata

ID: csharp-best-practices/tostring-not-return-null

Language: C#

Severity: Warning

Category: Error Prone

Description

The method ToString() should always return a value (for example, a string) and never return null. Instead of returning null, return string.Empty, which is an empty string.

Non-Compliant Code Examples

class MyClass {
    public override string ToString()
    {
        if(foo) {
            return null;
        }
        return null;
        
    }
}

class MyClass {
    public override string ToString()
    {
        return null;
    }
}

Compliant Code Examples

class MyClass {
    public override string ToString()
    {
        return string.Empty;;    
    }
}

How to use this rule

1
2
rulesets:
  - csharp-best-practices     # Rules to enforce C# best practices.

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