C++ Keywords
C++ Keywords
A list of all C++ keywords can be found in the table below.
| Keyword | Description |
|---|---|
| alignas | Specifies the alignment (the memory address boundary) of a variable or type |
| alignof | Returns the alignment of a type, in bytes |
| and | An alternative way to write the logical && operator |
| and_eq | An alternative way to write the &= assignment operator |
| asm | Lets you write assembly code (low-level processor instructions) inside C++ code |
| auto | Automatically detects the type of a variable based on the value you assign to it |
| bitand | An alternative way to write the & bitwise operator |
| bitor | An alternative way to write the | bitwise operator |
| bool | A data type that can only store true or false values |
| break | Breaks out of a loop or a switch block |
| case | Marks a block of code in switch statements |
| catch | Catches exceptions generated by try statements |
| char | A data type that can store a single character |
| char16_t | A data type that can store a 16-bit character, used for UTF-16 text |
| char32_t | A data type that can store a 32-bit character, used for UTF-32 text |
| class | Defines a class |
| compl | An alternative way to write the ~ bitwise operator |
| const | Defines a variable or parameter as a constant (unchangeable) or specifies that a class method does not modify attributes of the class |
| const_cast | Converts a value by adding or removing const |
| constexpr | Specifies that the value of a variable or function can be calculated when the program is compiled |
| continue | Continues to the next iteration of a loop |
| decltype | Gets the type of an expression, so you can declare a variable with the same type |
| default | Specifies the default block of code in a switch statement |
| delete | Frees dynamic memory |
| do | Used together with while to create a do/while loop |
| double | A data type that is usually 64 bits long which can store fractional numbers |
| dynamic_cast | Converts a pointer or reference from a parent class to a child class, and checks that it is safe while the program runs |
| else | Used in conditional statements |
| enum | Declares an enumerated type |
| explicit | Prevents a constructor from being used for automatic (implicit) type conversions |
| export | Reserved for future use (C++20 uses it for modules) |
| extern | Declares a variable or function that is defined in another file |
| false | A boolean value equivalent to 0 |
| final | Prevents a class from being inherited, or a virtual method from being overridden |
| float | A data type that is usually 32 bits long which can store fractional numbers |
| for | Creates a for loop |
| friend | Specifies classes and functions which have access to private and protected members |
| goto | Jumps to a line of code specified by a label |
| if | Makes a conditional statement |
| inline | Suggests to the compiler that the code of a function should be inserted where the function is called |
| int | A data type that is usually 32 bits long which can store whole numbers |
| long | Ensures that an integer is at least 32 bits long (use long long to ensure 64 bits) |
| mutable | Allows an attribute to be changed, even in a const object or method |
| namespace | Declares a namespace |
| new | Reserves dynamic memory |
| noexcept | Specifies that a function does not throw exceptions |
| not | An alternative way to write the logical ! operator |
| not_eq | An alternative way to write the != comparison operator |
| nullptr | A pointer value that does not point to anything |
| operator | Defines how an operator, like +, works for a class (operator overloading) |
| or | An alternative way to write the logical || operator |
| or_eq | An alternative way to write the |= assignment operator |
| override | Specifies that a method overrides a virtual method from the parent class |
| private | An access modifier which makes a member only accessible within the declared class |
| protected | An access modifier which makes a member only accessible within the declared class and its children |
| public | An access modifier which makes a member accessible from anywhere |
| register | Not used since C++17, but the word is still reserved. It was used to suggest that a variable should be stored in a CPU register |
| reinterpret_cast | Converts a pointer to an unrelated pointer type (a low-level conversion) |
| return | Used to return a value from a function |
| short | Reduces the size of an integer to 16 bits |
| signed | Specifies that an int or char can represent positive and negative values (this is the default so the keyword is not usually necessary) |
| sizeof | An operator that returns the amount of memory occupied by a variable or data type |
| static |
Specifies that an attribute or method belongs to the class itself instead of instances of the class Specifies that a variable in a function keeps its value after the function ends |
| static_assert | Checks a condition when the program is compiled, and stops with an error message if it is false |
| static_cast | Converts a value from one type to another, like a double to an int |
| struct | Defines a structure |
| switch | Selects one of many code blocks to be executed |
| template | Declares a template class or template function |
| this | A variable that is available inside class methods and constructors which contains a pointer to a class instance |
| thread_local | Specifies that each thread has its own copy of a variable |
| throw | Creates a custom error which can be caught by a try...catch statement |
| true | A boolean value equivalent to 1 |
| try | Creates a try...catch statement |
| typedef | Defines a custom data type |
| typeid | Returns information about the type of a variable or expression |
| typename | Declares a type parameter in a template, or tells the compiler that a name is a type |
| union | Defines a union, a type where all members share the same memory |
| unsigned | Specifies that an int or char should only represent positive values which allows for storing numbers up to twice as large |
| using | Allows variables and functions from a namespace to be used without the namespace's prefix |
| virtual | Specifies that a class method is virtual |
| void | Indicates a function that does not return a value or specifies a pointer to a data with an unspecified type |
| volatile | Tells the compiler that a variable can change at any time, for example by hardware, so it must always read the value from memory |
| wchar_t | A data type that can store a wide character, which can be larger than a char |
| while | Creates a while loop |
| xor | An alternative way to write the ^ bitwise operator |
| xor_eq | An alternative way to write the ^= assignment operator |
Note: override and final are not reserved words, so you can still use them as names. They only have a special meaning in a class.
Note: The table lists the keywords in C++11. Newer versions of C++ added a few more, like concept, requires and co_await (C++20).
