Standard library header <stdarg.h> - cppreference.com

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This header provides support for varying arguments.

Types
holds the information needed by va_start, va_arg, va_end, and va_copy
(typedef) [edit]
Macros
enables access to variadic function arguments
(function macro) [edit]
accesses the next variadic function argument
(function macro) [edit]
makes a copy of the variadic function arguments
(function macro) [edit]
ends traversal of the variadic function arguments
(function macro) [edit]

Synopsis

#define __STDC_VERSION_STDARG_H__ 202311L

typedef /*unspecified*/ va_list;

/*type*/ va_arg(va_list ap, /*type*/);
void va_copy(va_list dest, va_list src);
void va_end(va_list ap);
void va_start(va_list ap, ...);