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1. C++ Identifier Not Found
2. Dev C++ Online
3. Dev C++ 5.11
4. C++ Identifier Class Is Undefined
5. Dev C Identifier List

Result of + operator identifier: 52 Result of - identifier: 32 In the above example +, – are the operator identifiers which adds and subtracts the variables and prints the result. Mixed Identifiers; A mixed identifier contains alphanumeric character followed by underscore and an operator identifier. Example unary+, myVar=. A C identifier is a name used to identify a variable, function, class, module, or any other user-defined item. An identifier starts with a letter A to Z or a to z or an underscore followed by zero or more letters, underscores, and digits (0 to 9). C does not allow punctuation characters such as @, $, and% within identifiers.

The #define creates a macro, which is the association of an identifier or parameterized identifier with a token string. After the macro is defined, the compiler can substitute the token string for each occurrence of the identifier in the source file.

Syntax

#defineidentifiertoken-string_opt
#defineidentifier(identifier_opt, ... ,identifier_opt)token-string_opt

Remarks

The #define directive causes the compiler to substitute token-string for each occurrence of identifier in the source file. The identifier is replaced only when it forms a token. That is, identifier is not replaced if it appears in a comment, in a string, or as part of a longer identifier. For more information, see Tokens.

The token-string argument consists of a series of tokens, such as keywords, constants, or complete statements. One or more white-space characters must separate token-string from identifier. This white space is not considered part of the substituted text, nor is any white space that follows the last token of the text.

A #define without a token-string removes occurrences of identifier from the source file. The identifier remains defined and can be tested by using the #if defined and #ifdef directives.

The second syntax form defines a function-like macro with parameters. This form accepts an optional list of parameters that must appear in parentheses. After the macro is defined, each subsequent occurrence of identifier( identifier_opt, ..., identifier_opt ) is replaced with a version of the token-string argument that has actual arguments substituted for formal parameters.

Formal parameter names appear in token-string to mark the locations where actual values are substituted. Each parameter name can appear multiple times in token-string, and the names can appear in any order. The number of arguments in the call must match the number of parameters in the macro definition. Liberal use of parentheses guarantees that complex actual arguments are interpreted correctly.

The formal parameters in the list are separated by commas. Each name in the list must be unique, and the list must be enclosed in parentheses. No spaces can separate identifier and the opening parenthesis. Use line concatenation — place a backslash () immediately before the newline character — for long directives on multiple source lines. The scope of a formal parameter name extends to the new line that ends token-string.

C++ Identifier Not Found

When a macro has been defined in the second syntax form, subsequent textual instances followed by an argument list indicate a macro call. The actual arguments that follows an instance of identifier in the source file are matched to the corresponding formal parameters in the macro definition. Each formal parameter in token-string that is not preceded by a stringizing (#), charizing (#@), or token-pasting (##) operator, or not followed by a ## operator, is replaced by the corresponding actual argument. Any macros in the actual argument are expanded before the directive replaces the formal parameter. (The operators are described in Preprocessor operators.)

The following examples of macros with arguments illustrate the second form of the #define syntax:

Arguments with side effects sometimes cause macros to produce unexpected results. A given formal parameter may appear more than one time in token-string. If that formal parameter is replaced by an expression with side effects, the expression, with its side effects, may be evaluated more than one time. (See the examples under Token-Pasting Operator (##).)

The #undef directive causes an identifier's preprocessor definition to be forgotten. See The #undef Directive for more information.

If the name of the macro being defined occurs in token-string (even as a result of another macro expansion), it is not expanded.

A second #define for a macro with the same name generates a warning unless the second token sequence is identical to the first.

Microsoft Specific

Microsoft C/C++ lets you redefine a macro if the new definition is syntactically identical to the original definition. In other words, the two definitions can have different parameter names. This behavior differs from ANSI C, which requires that the two definitions be lexically identical.

For example, the following two macros are identical except for the parameter names. ANSI C does not allow such a redefinition, but Microsoft C/C++ compiles it without error.

On the other hand, the following two macros are not identical and will generate a warning in Microsoft C/C++.

END Microsoft Specific

This example illustrates the #define directive:

The first statement defines the identifier WIDTH as the integer constant 80 and defines LENGTH in terms of WIDTH and the integer constant 10. Each occurrence of LENGTH is replaced by (WIDTH + 10). In turn, each occurrence of WIDTH + 10 is replaced by the expression (80 + 10). The parentheses around WIDTH + 10 are important because they control the interpretation in statements such as the following:

After the preprocessing stage the statement becomes:

which evaluates to 1800. Without parentheses, the result is:

which evaluates to 280.

Microsoft Specific

Defining macros and constants with the /D compiler option has the same effect as using a #define preprocessing directive at the start of your file. Up to 30 macros can be defined by using the /D option.

END Microsoft Specific

See also

In C, C++, C# and other programming languages, an identifier is a name that is assigned by the user for a program element such as variable, type, template, class, function or namespace. It is usually limited to letters, digits, and underscores. Certain words, such as 'new,' 'int' and 'break,' are reserved keywords and cannot be used as identifiers. Identifiers are used to identify a program element in the code.

Computer languages have restrictions for which characters can appear in an identifier. For example, in early versions of the C and C++ languages, identifiers were restricted to a sequence of one or more ASCII letters, digits, which may not appear as the first character, and underscores. Later versions of these languages support almost all Unicode characters in an identifier with the exception of white space characters and language operators.

You designate an identifier by declaring it early in the code. Then, you can use that identifier later in the program to refer to the value you assigned to the identifier.

Rules for Identifiers

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When naming an identifier, follow these established rules:

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• An identifier cannot be a C# keyword. Keywords have predefined special meanings to the compiler.
• It cannot have two consecutive underscores.
• It can be a combination of numbers, letters, connectors, and Unicode characters.
• It must start with a letter of the alphabet or an underscore, not a number.
• It should not include white space.
• It cannot have more than 511 characters.
• It has to be declared before it is referred.
• Two identifiers cannot have the same name.
• Identifiers are case sensitive.

For implementations of programming languages that are compiled, identifiers are often only compile-time entities. That is, at run time the compiled program contains references to memory addresses and offsets rather than the textual identifier tokens—these memory addresses or offsets having been assigned by the compiler to each identifier.

C++ Identifier Class Is Undefined

Verbatim Identifiers

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Adding the prefix '@' to a keyword enables the keyword, which is normally reserved, to be used as an identifier, which can be useful when interfacing with other programming languages. The @ is not considered part of the identifier, so it might not be recognized in some languages. It is a special indicator to not treat what comes after it as a keyword, but rather as an identifier. This type of identifier is called a verbatim identifier. Using verbatim identifiers is allowed but strongly discouraged as a matter of style.