[logic.error]

# 19 Diagnostics library [[diagnostics]](./#diagnostics)

## 19.2 Exception classes [[std.exceptions]](std.exceptions#logic.error)

### 19.2.3 Class logic_error [logic.error]

[🔗](#lib:logic_error)

namespace std {class logic_error : public exception {public:constexpr explicit logic_error(const string& what_arg); constexpr explicit logic_error(const char* what_arg); };}

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/diagnostics.tex#L91)

The classlogic_error defines the type of objects thrown as
exceptions to report errors presumably detectable before
the program executes, such as violations of logical preconditions or class
invariants[.](#1.sentence-1)

[🔗](#lib:logic_error,constructor)

`constexpr logic_error(const string& what_arg);
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/diagnostics.tex#L105)

*Postconditions*: strcmp(what(), what_arg.c_str()) == 0[.](#2.sentence-1)

[🔗](#lib:logic_error,constructor_)

`constexpr logic_error(const char* what_arg);
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/diagnostics.tex#L116)

*Postconditions*: strcmp(what(), what_arg) == 0[.](#3.sentence-1)