# Compiler Error CS1040

Preprocessor directives must appear as the first non-white-space character on a line

A preprocessor directive was found on a line and was not the first token on the line. A directive must be the first token on the line.

The following sample generates CS1040:

// CS1040.cs
/* Define a symbol, X */ #define X   // CS1040

// try the following two lines instead
// /* Define a symbol, X */
// #define X

public class MyClass
{
public static void Main()
{
}
}