What is __ Va_args __ C++?

What is __ Va_args __ C++?

macro expansion possible specifying __VA_ARGS__ The ‘…’ in the parameter list represents the variadic data when the macro is invoked and the __VA_ARGS__ in the expansion represents the variadic data in the expansion of the macro. Variadic data is of the form of 1 or more preprocessor tokens separated by commas.

Is printf variadic function?

The C printf() function is implemented as a variadic function. This noncompliant code example swaps its null-terminated byte string and integer parameters with respect to how they are specified in the format string.

What is argc and argv?

The first parameter, argc (argument count) is an integer that indicates how many arguments were entered on the command line when the program was started. The second parameter, argv (argument vector), is an array of pointers to arrays of character objects.

What is va_list in C?

va_list is a complete object type suitable for holding the information needed by the macros va_start, va_copy, va_arg, and va_end. If a va_list instance is created, passed to another function, and used via va_arg in that function, then any subsequent use in the calling function should be preceded by a call to va_end.

Why are macros used in C?

In C, the macro is used to define any constant value or any variable with its value in the entire program that will be replaced by this macro name, where macro contains the set of code that will be called when the macro name is used in the program.

What is Va_list in C?

What is a variadic in C?

Variadic functions are functions that can take a variable number of arguments. In C programming, a variadic function adds flexibility to the program. It takes one fixed argument and then any number of arguments can be passed.

What is variadic parameters in Swift?

Variadic Parameters A variadic parameter accepts zero or more values of a specified type. You use a variadic parameter to specify that the parameter can be passed a varying number of input values when the function is called.

What is the purpose of argv?

What is ARGV? As a concept, ARGV is a convention in programming that goes back (at least) to the C language. It refers to the “argument vector,” which is basically a variable that contains the arguments passed to a program through the command line.

What is Va_start macro?

The va_start macro enables access to the variable arguments following the named argument parm_n . va_start should be invoked with an instance to a valid va_list object ap before any calls to va_arg.

What is macros in C language?

A macro is a fragment of code that is given a name. You can define a macro in C using the #define preprocessor directive. Here’s an example. Here, when we use c in our program, it is replaced with 299792458 .