Can macros have parameters in C?
Function-like macros can take arguments, just like true functions. To define a macro that uses arguments, you insert parameters between the pair of parentheses in the macro definition that make the macro function-like. The parameters must be valid C identifiers, separated by commas and optionally whitespace.
What is macro in C with example?
A macro is a segment of code which is replaced by the value of macro. Macro is defined by #define directive. There are two types of macros: Object-like Macros….C Predefined Macros.
| No. | Macro | Description |
|---|---|---|
| 1 | _DATE_ | represents current date in “MMM DD YYYY” format. |
| 2 | _TIME_ | represents current time in “HH:MM:SS” format. |
How #define works in C?
In the C Programming Language, the #define directive allows the definition of macros within your source code. These macro definitions allow constant values to be declared for use throughout your code. You generally use this syntax when creating constants that represent numbers, strings or expressions.
Where macros are stored in C?
Macros are not stored in memory anywhere in the final program but instead the code for the macro is repeated whenever it occurs. As far as the actual compiler is concerned they don’t even exist, they’ve been replaced by the preprocessor before they get that far.
What type of parameters are used for macro expansion?
Macro definition and Expansion A macro consists of name, set of formal parameters and body of code. The use of macro name with set of actual parameters is replaced by some code generated by its body. This is called macro expansion.
What is ## operator in C?
Token-pasting operator (##) The ‘##’ pre-processing operator performs token pasting. When a macro is expanded, the two tokens on either side of each ‘##’ operator are combined into a single token, which then replaces the ‘##’ and the two original tokens in the macro expansion.
How many types of macros are there in C?
two types
Macro is defined by #define directive. There are two types of macros: Object-like Macros. Function-like Macros.
Is the only macro parameter a variable argument?
The above explanation is ambiguous about the case where the only macro parameter is a variable arguments parameter, as it is meaningless to try to distinguish whether no argument at all is an empty argument or a missing argument. CPP retains the comma when conforming to a specific C standard.
When does a variadic macro become a variable?
This kind of macro is called variadic. When the macro is invoked, all the tokens in its argument list after the last named argument (this macro has none), including any commas, become the variable argument. This sequence of tokens replaces the identifier __VA_ARGS__ in the macro body wherever it appears.
How to stringize an argument in a variadic macro?
The variable argument is completely macro-expanded before it is inserted into the macro expansion, just like an ordinary argument. You may use the ‘#’ and ‘##’ operators to stringize the variable argument or to paste its leading or trailing token with another token.
When do you use variable arguments in C?
C – Variable Arguments. Sometimes, you may come across a situation, when you want to have a function, which can take variable number of arguments, i.e., parameters, instead of predefined number of parameters.