Q:

How to use #ifdef for data type switching

I am using visual studio c++. I want to be able to switch between double and long long.
How can I use #ifdef in the following program? I want to use a more simpler solution to handle the case of multiple printf.
//#define TYPE_SWITCH
#ifdef TYPE_SWITCH
      typedef double myType;
#else
      typedef long long myType;
#end

.
.
.
int main()
{
     myType a;
     #ifdef TYPE_SWITCH
        printf ("my value is %lf",a);      // I have many printf or scanf and I want to use a simple macro here
     #else
        printf ("your value is %l",a/10);      // I have many printf or scanf and I want to use a simple macro here
     #endif

}

A:

You could use something like that:
//#define TYPE_SWITCH
#ifdef TYPE_SWITCH
      typedef double myType;
      #def PATTERN_MY_TYPE "%lf"
      #def MODIFICATOR(a) (a)
#else
      typedef long long myType;
      #def PATTERN_MY_TYPE "%l"
      #def MODIFICATOR(a) (a/10)
#end
#def PATTERN_INT "%d"

//...

int main() {
     myType a;
     printf(PATTERN_MY_TYPE ", " PATTERN_INT, MODIFICATOR(a), 42);
}

The compeiler can concate strings while compeiling so you can use "foo" "bar" to create the string "foobar" the same works for defines. ("foo" PATTERN_INT "bar" would produce "foo%dbar".

