Stringification operator
The stringification operator is the C preprocessor operator # that converts a macro argument's textual spelling into a string literal.
Modern C, Third Edition
Macro argument stringification is the C preprocessing technique of converting a macro argument's textual spelling into a string literal.
- How it is used
- Supports compile-time diagnostic and tracing macros by preserving the caller's expression spelling.
- How deep it goes
- Explains textual conversion, suppressed argument expansion, and the two-layer workaround, but stops short of preprocessing implementation internals.
- Examples
- Uses STRINGIFY, STRGY, TRACE_PRINT5, __LINE__, expressions, and variadic arguments as concrete examples.
- What you can do after
- Apply it via C macros to emit expression text and safely stringify values such as expanded line numbers.
Read how Modern C, Third Edition explains stringification operator →
Modern C
Stringification is the preprocessing technique of converting a macro argument's tokens into a string literal.
- How it is used
- Supports debugging macros by recording source expressions, line numbers, function names, and variadic argument text in trace output.
- How deep it goes
- Explains textual replacement, nonexpansion, and two-level indirection through trace macros, while deferring broader preprocessing details.
- Examples
- Uses TRACE_PRINT5 and TRACE_PRINT9 to label sum, sum*argc, line numbers, and variadic expressions in diagnostic output.
- What you can do after
- Apply it via C preprocessing to build trace macros that print source expressions and expanded line numbers alongside evaluated values.
Related concepts
- __VA_ARGS__used by · __VA_ARGS__ is the predefined C preprocessor identifier that expands to arguments supplied for a variadic macro’s ellipsis parameter.
- macro parameteruses · A macro parameter is a named placeholder in a macro definition that receives the corresponding argument from a macro invocation for expansion.
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