[replacement.functions]

# 16 Library introduction [[library]](./#library)

## 16.4 Library-wide requirements [[requirements]](requirements#replacement.functions)

### 16.4.5 Constraints on programs [[constraints]](constraints#replacement.functions)

#### 16.4.5.6 Replacement functions [replacement.functions]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lib-intro.tex#L3405)

If a function defined in[[support]](support "17 Language support library") through [[exec]](exec "33 Execution control library") and [[depr]](depr "Annex D (normative) Compatibility features") is specified as replaceable ([[dcl.fct.def.replace]](dcl.fct.def.replace#term.replaceable.function "9.6.5 Replaceable function definitions")),
the description of function semantics apply
to both the default version defined by the C++ standard library and
the replacement function defined by the program[.](#1.sentence-1)