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When a Script or Template is executed, a special preprocessor stage is run before the main compilation of the file begins. In the preprocessor stage, the software finds any preprocessor directives (e.g. #include, #ifdef, #define, etc.) and uses them to modify the text of the original source code. Each preprocessor directive must start with a '#' character and the '#' character must be the first non-whitespace character on a line.


Special preprocessor constants can be defined using the syntax '#define <constant_name> [ <text_value> ]'. For example:

    #define PI 3.14159265

Note that a semi-colon is not required after the statement. When any occurrence of the defined constant name is encountered in the rest of the source code (except inside of a string), it will be textually replaced with the defined value of the constant. For example:

    Printf( "ToRadians=%lf\n", 90.0 * (PI/180.0) );

When defining a constant, a value is not required after the constant name in which case a constant is still defined but it will have an empty value. The constant value can be any text string and multi-line values can be defined by placing a '\' character as the last character of a value line. For example:

    #define CHECK_VALUE if( value > 5) { \
        Printf( "Invalid value %d\n", value ); \
        Exit(-1); }
    int value = 4;
    value = 10;

Constants created with #define can also include other constants that have previously been created with #define. For example:

    #define FILE_ICON   12
    #define FOLDER_ICON (FILE_ICON+100)

Any constants that are defined can be undefined later using the syntax '#undef <constant_name>'. Note that some preprocessors support macros with #define statements but this is not currently supported in 010 Editor.

Built-in Constants

The following constants are defined automatically in 010 Editor depending upon which version of 010 Editor is being run:
  • _010EDITOR - always defined when running 010 Editor.

  • _010_WIN - defined if running the Windows version of 010 Editor.

  • _010_MAC - defined if running the Macintosh version of 010 Editor.

  • _010_LINUX - defined if running a Linux version of 010 Editor.

  • _010_64BIT - defined if 010 Editor is being run in 64-bit mode.

Conditional Compilation

The preprocessor directives #ifdef and #ifndef can be used to compile or ignore whole sections of source code depending on if certain constants were defined with the #define directive above. The syntax for these commands is:

    #ifdef | #ifndef <constant_name>
    [ #else ]

A common usage of this syntax is to place code such as:

    #ifndef CONSTANTS_H
    #define CONSTANTS_H

at the beginning of a header file (e.g. constants.h) and then an '#endif' statement at the end of the header file. Then, if this header file is included twice into the source code with #include (see below), the code inside the header file will only be compiled once (the second time the file is included the constant CONSTANTS_H is already defined so the #ifndef statement skips the rest of the code). Note that multiple #ifdef or #ifndef statements can be nested inside of each other, but make sure the #endif statements properly line up with the #ifdef/#ifndef statements.

Warnings and Errors

The preprocessor directive #warning can be used to output a message to the Output tab of the Output Window during compilation with the syntax '#warning "<message>"'. For example:

    #ifdef NUMBITS
        value = value + NUMBITS;
    #warning "NUMBITS not defined!"

The #error directive is similar to the #warning directive except compilation will stop once an #error directive is reached. For example:

    #ifndef CURRENT_OS
    #error  "CURRENT_OS must be defined. Compilation stopped."


The #include directive is supported to insert additional text files into the current file. This directive is discussed in the separate Includes help topic.

External Functions

The #link/#endlink directive can be used to call functions inside an external DLL. See the External (DLL) Functions in Scripts help topic for more information.

This is the manual for 010 Editor, a professional hex editor and text editor. Use 010 Editor to edit the individual bytes of any binary file, hard drive, or process on your machine. 010 Editor contains a whole host of powerful analysis and editing tools, plus Binary Templates technology that allows any binary format to be understood.

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