CODEWITHSUNDEEP
c++variablesmacros
elite21
elite21

Reputation: 817

Forming variable name with Macro

Can I do something like this:

#define VERSION 4_1

int32_t myVersion??VERSION;

// What I expect here is that the variable should be generated with name myVersion4_1.
// If possible what should be placed instead of ?? above?

Is it possible to form variable name using Macro like above in C++?

Upvotes: 1

Views: 145

Answers (2)

Piotr Skotnicki
Piotr Skotnicki

Reputation: 48527

Not exactly how you try, but you can do what follows:

#define VAR_VERSIONED_NAME(name) name##4_1

int32_t VAR_VERSIONED_NAME(myVersion) = 1;
myVersion4_1 = 2;

or if a VERSION must be a separate define:

#define VERSION 4_1

#define CAT_I(a, b) a ## b
#define CAT(a, b) CAT_I(a, b)
#define VAR_VERSIONED_NAME(name) CAT(name, VERSION)

int VAR_VERSIONED_NAME(myVersion) = 1;
myVersion4_1 = 2;

Upvotes: 3

user3920237
user3920237

Reputation:

You need a level of indirection to expand VERSION before you can paste it.

#define VERSION 4_1

#define expand(v) paste(v)
#define paste(v) myVersion ## v

int main()
{
    int expand(VERSION);
    myVersion4_1 = 42;
}

Upvotes: 1

Related Questions