Compiler warnings are useful for catching potential problems but sometimes a warning is intentional or unavoidable. In C# 1.0 the only options were to disable the warning for the entire project via compiler switches or to live with the noise.

C# 2.0 adds #pragma warning directives to suppress and restore specific warnings at the source level, keeping the rest of the codebase protected.

Code

Now

#pragma warning disable 0168 // variable declared but never used
int unusedButRequired;
#pragma warning restore 0168

// Warnings are back in effect here

Before

int unusedButRequired; // Compiler warning CS0168 with no way to suppress locally

Notes

• #pragma warning disable without a warning number suppresses all warnings for the following code - use this sparingly
• #pragma warning restore re-enables warnings - always restore after disabling to limit the scope
• Current compilers also accept the CS prefix (e.g. CS0168) and analyzer rule IDs (e.g. CA1234)
• C# 2.0 also added #pragma checksum, used by tools such as ASP.NET to help the debugger match generated code to its source file
• See Experimental attribute ^{C# 12.0} for the attribute that produces a warning suppressed with the same directive.

More information

• C# Language Reference