---
name: "dwarf_def_macro"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/dwarf_def_macro"
---

# dwarf\_def\_macro(3)

add a macro definition to a DWARF producer instance

## NAME

**dwarf\_def\_macro** – add a macro definition to a DWARF producer instance

## LIBRARY

library “libdwarf”

## SYNOPSIS

**#include \<libdwarf.h\>**

*int*\

**dwarf\_def\_macro**(*Dwarf\_P\_Debug dbg*, *Dwarf\_Unsigned lineno*, *char \*name*, *char \*value*, *Dwarf\_Error \*err*);

## DESCRIPTION

Function **dwarf\_def\_macro**() adds a macro definition to a DWARF producer instance.

Argument *dbg* should reference a DWARF producer instance allocated using [dwarf\_producer\_init(3)](/dwarf_producer_init/3.md) or [dwarf\_producer\_init\_b(3)](/dwarf_producer_init_b/3.md).

Argument *lineno* specifies the line number of the source line where the macro is defined. A line number of zero is used for macros that are defined before any source file is read.

Argument *name* should point to a NUL-terminated string containing the name of the macro. For function-like macros this parameter should also include parentheses and parameter names if any.

Argument *value* should point to a NUL-terminated string containing the value of the macro. If the macro does not have a value, argument *value* should be set to NULL.

If argument *err* is not NULL, it will be used to store error information in case of an error.

## RETURN VALUES

On success, function **dwarf\_def\_macro**() returns DW\_DLV\_OK. In case of an error, function **dwarf\_def\_macro**() returns DW\_DLV\_ERROR and sets the argument *err*.

## EXAMPLES

To record the fact that a macro named \_STDIO\_H\_ was defined at line 20 of the current macro file, use:

```
Dwarf_P_Debug dbg;
Dwarf_Error de;
/* ... Assume 'dbg' refers to a DWARF producer instance... */
if (dwarf_def_macro(dbg, 20, "_STDIO_H_", NULL, &de) != DW_DLV_OK)
	errx(EXIT_FAILURE, "dwarf_def_macro failed: %s",
	    dwarf_errmsg(-1));
```

## ERRORS

Function **dwarf\_def\_macro**() can fail with:

- \[DW\_DLE\_ARGUMENT\]

  Either arguments *dbg* or *name* was NULL.

- \[DW\_DLE\_MEMORY\]

  An out of memory condition was encountered during the execution of the function.

## SEE ALSO

[dwarf(3)](/dwarf/3.md), [dwarf\_end\_macro\_file(3)](/dwarf_end_macro_file/3.md), [dwarf\_producer\_init(3)](/dwarf_producer_init/3.md), [dwarf\_producer\_init\_b(3)](/dwarf_producer_init_b/3.md), [dwarf\_start\_macro\_file(3)](/dwarf_start_macro_file/3.md), [dwarf\_undef\_macro(3)](/dwarf_undef_macro/3.md), [dwarf\_vendor\_ext(3)](/dwarf_vendor_ext/3.md)