unprotoize

Additional Notes

unprotoize is part of the GNU Compiler Collection (GCC) and converts ANSI C (C89/C99) function definitions and declarations back to the older K&R (Kernighan & Ritchie) style. It is the inverse of protoize, which adds prototypes to K&R-style code.

This tool is rarely used today. It was designed for migrating code between K&R and ANSI C standards during the transition period in the late 1980s and 1990s. Modern C code universally uses ANSI-style prototypes. The tool exists primarily for historical codebases that need to be compiled with pre-ANSI compilers.

Syntax

unprotoize [options] [files]

Parameters

• files: C source files to convert. Supports wildcards.

Common Options

• -c: Do not generate line directives in the output.
• -g: Add global declarations for external function prototypes.
• -k: Keep the static keyword for file-scope functions.
• -p prog: Use the specified preprocessor program.
• -N: Do not generate comments indicating the source of parameters.
• -v: Verbose output.

Examples

unprotoize *.c

Convert all C files in the current directory from ANSI to K&R style.

unprotoize -v file.c

Convert file.c with verbose output.

Practical Notes

• unprotoize is part of GCC but may not be installed by default on modern systems.
• It requires a working GCC installation because it uses the GCC preprocessor and internal representation.
• Make backups before running unprotoize on important source code.
• The converted code may need manual adjustments for correctness.
• For modern projects, there is no reason to use unprotoize unless targeting a pre-ANSI compiler.