### Initial Sequence of Headers

The initial sequence of headers can consist of any of the following:

- #include directives
- comments
- error directives
- null directives
- false conditional compilation blocks beginning with elif or else
- #endif directives

The first #include directive can be preceded only by comments and preprocessing directives. If anything else precedes it, the compiler does not create or attempt to use precompiled headers with that source file.

The initial sequence is ended by any construct not in the list, or by the occurrence of a #pragma hdrstop. If you use #pragma hdrstop before the first #include directive, there is no initial sequence.

Any #include directives after the initial sequence are not precompiled; they will be compiled every time you compile the source file.

When a header contains conditional compilation directives to prevent it from being included a second time, it is only counted once in the initial sequence, even if it appears more than once.

Precompiled Headers

Create Precompiled Header Files

Example of an Initial Sequence