< cpp | language
- Qt Static Assertion Failed Signal And Slot Arguments Are Not Compatible
Debugging Pascal programs which use sets, subranges, file variables, or nested functions does not currently work. GDB does not support entering expressions, printing values, or similar features using Pascal syntax. GDB can be used to debug programs written in Fortran, although it may be necessary to refer to some variables with a trailing. May 25, 2018 Qt/C Tutorial 080. Downloading large files with QNetworkAccessManager. After the question appeared on the forum about downloading large files using the Qt library, I raised some of my projects and prepared a more detailed manual using this functionality.
C++
| Language |
| Standard Library Headers |
| Freestanding and hosted implementations |
| Named requirements |
| Language support library |
| Concepts library(C++20) |
| Diagnostics library |
| Utilities library |
| Strings library |
| Containers library |
| Iterators library |
| Ranges library(C++20) |
| Algorithms library |
| Numerics library |
| Input/output library |
| Localizations library |
| Regular expressions library(C++11) |
| Atomic operations library(C++11) |
| Thread support library(C++11) |
| Filesystem library(C++17) |
| Technical Specifications |
Declarations
| Overview | | declaration syntax | | decl-specifier-seq | | declarator | | Specifiers | | virtual function specifier | | explicit function specifier | (C++11) | (C++20) | (C++20) | | storage class specifiers | (C++11) | (C++11) | (C++11) | | elaborated type specifier | | attributes (C++11) |
| | Declarators | | reference | | pointer | | array | | Block declarations | | simple-declaration | | → structured binding declaration(C++17) | | alias declaration(C++11) | | namespace alias definition | | using-declaration | | using-directive | | static_assert declaration(C++11) | | asm-declaration | | opaque enum declaration(C++11) | | Other declarations | | namespace definition | | function declaration | | class template declaration | | function template declaration | | explicit template instantiation(C++11) | | explicit template specialization | | linkage specification | | attribute declaration(C++11) | | empty declaration |
|
Performs compile-time assertion checking
Qt Static Assertion Failed Signal And Slot Arguments Are Not Compatible
[edit]Syntax
static_assert(bool_constexpr,message) | (since C++11) |
static_assert(bool_constexpr) | (since C++17) |
[edit]Explanation
| bool_constexpr | - | a contextually converted constant expression of type bool |
| message | - | optional (since C++17)string literal that will appear as compiler error if bool_constexpr is false |
A static assert declaration may appear at namespace and block scope (as a block declaration) and inside a class body (as a member declaration)
If bool_constexpr returns true, this declaration has no effect. Otherwise a compile-time error is issued, and the text of message, if any, is included in the diagnostic message.
message can be omitted. | (since C++17) |
[edit]Note
Since message has to be a string literal, it cannot contain dynamic information or even a constant expression that is not a string literal itself. In particular, it cannot contain the name of the template type argument.
[edit]Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|
| CWG 2039 | C++11 | only the expression before conversion is required to be constant | the conversion must also be valid in a constant expression |
[edit]Example
Possible output:
[edit]See also
C documentation for static_assert |
Retrieved from 'https://en.cppreference.com/mwiki/index.php?title=cpp/language/static_assert&oldid=109785'
< cpp | language
C++
| Language |
| Standard Library Headers |
| Freestanding and hosted implementations |
| Named requirements |
| Language support library |
| Concepts library(C++20) |
| Diagnostics library |
| Utilities library |
| Strings library |
| Containers library |
| Iterators library |
| Ranges library(C++20) |
| Algorithms library |
| Numerics library |
| Input/output library |
| Localizations library |
| Regular expressions library(C++11) |
| Atomic operations library(C++11) |
| Thread support library(C++11) |
| Filesystem library(C++17) |
| Technical Specifications |
Declarations
| Overview | | declaration syntax | | decl-specifier-seq | | declarator | | Specifiers | | virtual function specifier | | explicit function specifier | (C++11) | (C++20) | (C++20) | | storage class specifiers | (C++11) | (C++11) | (C++11) | | elaborated type specifier | | attributes (C++11) |
| | Declarators | | reference | | pointer | | array | | Block declarations | | simple-declaration | | → structured binding declaration(C++17) | | alias declaration(C++11) | | namespace alias definition | | using-declaration | | using-directive | | static_assert declaration(C++11) | | asm-declaration | | opaque enum declaration(C++11) | | Other declarations | | namespace definition | | function declaration | | class template declaration | | function template declaration | | explicit template instantiation(C++11) | | explicit template specialization | | linkage specification | | attribute declaration(C++11) | | empty declaration |
|
Performs compile-time assertion checking
[edit]Syntax
static_assert(bool_constexpr,message) | (since C++11) |
static_assert(bool_constexpr) | (since C++17) |
[edit]Explanation
| bool_constexpr | - | a contextually converted constant expression of type bool |
| message | - | optional (since C++17)string literal that will appear as compiler error if bool_constexpr is false |
A static assert declaration may appear at namespace and block scope (as a block declaration) and inside a class body (as a member declaration)
If bool_constexpr returns true, this declaration has no effect. Otherwise a compile-time error is issued, and the text of message, if any, is included in the diagnostic message.
message can be omitted. | (since C++17) |
[edit]Note
Since message has to be a string literal, it cannot contain dynamic information or even a constant expression that is not a string literal itself. In particular, it cannot contain the name of the template type argument.
[edit]Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|
| CWG 2039 | C++11 | only the expression before conversion is required to be constant | the conversion must also be valid in a constant expression |
[edit]Example
Possible output:
[edit]See also
C documentation for static_assert |
Retrieved from 'https://en.cppreference.com/mwiki/index.php?title=cpp/language/static_assert&oldid=109785'