The 
are identifiers that cannot be used as 
. These are reserved words used as instructions in a C/C++ program.
In this article , we have listed all the common keywords used in C/C++ language with a short description of each.
| Keyword | Language | Description |
| auto | C/C++ | Auto storage class |
| break | C/C++ | Break a loop or block |
| case | C/C++ | Part of switch-case |
| char | C/C++ | Declares char type |
| const | C/C++ | Declares a constant |
| continue | C/C++ | Continue a loop |
| default | C/C++ | Default switch-case |
| do | C/C++ | Do-while loop |
| double | C/C++ | Double data type |
| else | C/C++ | If-else block |
| enum | C/C++ | Enumeration type |
| extern | C/C++ | External storage class |
| float | C/C++ | Float data type |
| for | C/C++ | For loop |
| goto | C/C++ | Jump between blocks (Deprecated) |
| if | C/C++ | If block |
| int | C/C++ | Integer data type |
| long | C/C++ | Long data type |
| register | C/C++ | Register storage class |
| return | C/C++ | Returns a value |
| short | C/C++ | Short data type |
| signed | C/C++ | Data type with sign |
| sizeof | C/C++ | Returns sizeof variable |
| static | C/C++ | Static storage class |
| struct | C/C++ | Declare a structure |
| switch | C/C++ | Switch-Case block |
| typedef | C/C++ | User-defined type |
| union | C/C++ | Declare a union |
| unsigned | C/C++ | Unsigned data type |
| void | C/C++ | Void means no type |
| volatile | C/C++ | Variables stored in volatile memory |
| while | C/C++ | While loop |
The above keywords are common to both C and C++. See the list below for C++ specific keywords. C++ programming has more keywords because it supports object-oriented programming (OOP).
| Keyword | Language (C++) | Description |
| asm | C++ | gives ability to add assembly language code in C++ program |
| catch | C++ | part of try-catch block used for exception handling |
| class | C++ | declare a class |
| delete | C++ | delete an object |
| friend | C++ | declare friend function |
| inline | C++ | declare a code or block inline |
| new | C++ | create object dynamically with new |
| operator | C++ | used to overload C++ operators |
| private | C++ | visibility of class member set to private |
| protected | C++ | visibility of class member set to protected |
| public | C++ | visibility set to public |
| template | C++ | declares a template |
| this | C++ | reference to current class, where this is used |
| throw | C++ | throws a message, result of an exception and it is default or user-defined. |
| try | C++ | exception handling using try block |
| virtual | C++ | declare a function abstract using virtual, no implementation required for such a function. |
New sets of keyword is added by ASCI C++ which are listed in the following table.
| Keyword | Language (ASCI C++) | Description |
| bool | C++ | Boolean type with true or false value |
| const_cast | C++ | take away the constant-ness of an object. |
| dynamic_cast | C++ | cast the type at runtime |
| explicit | C++ | used with explicit constructors |
| export | C++ | used before template definition in C++ |
| false | C++ | Boolean value |
| mutable | C++ | storage class |
| namespace | C++ | functions, variables, and classes all can come under namespaces. |
| reinterpret_cast | C++ | integral type to pointer type conversion and vice-versa |
| static_cast | C++ | cast type easily at compile time |
| true | C++ | Boolean value |
| typeid | C++ | returns a typeinfo object |
| typename | C++ | used with C++ template |
| using | C++ | tells the namespace the C++ program uses |
| wchar_t | C++ | wide character type |