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#include <iostream>
#ifndef INIT_ARRAY_WITH_MACRO
# define DO_0(m, n)
# define DO_1(m, n) m((n))
# define DO_2(m, n) DO_1(m, n) DO_1(m, (n+1))
# define DO_4(m, n) DO_2(m, n) DO_2(m, (n+2))
# define DO_8(m, n) DO_4(m, n) DO_4(m, (n+4))
# define DO_16(m, n) DO_8(m, n) DO_8(m, (n+8))
# define DO_32(m, n) DO_16(m, n) DO_16(m, (n+16))
# define DO_64(m, n) DO_32(m, n) DO_32(m, (n+32))
# define DO_128(m, n) DO_64(m, n) DO_64(m, (n+64))
# define LIST_TO_SUM1(a1) LIST_TO_SUM8(a1, 0, 0, 0, 0, 0, 0, 0)
# define LIST_TO_SUM2(a1, a2) LIST_TO_SUM8(a1, a2, 0, 0, 0, 0, 0, 0)
# define LIST_TO_SUM3(a1, a2, a3) LIST_TO_SUM8(a1, a2, a3, 0, 0, 0, 0, 0)
# define LIST_TO_SUM4(a1, a2, a3, a4) LIST_TO_SUM8(a1, a2, a3, a4, 0, 0, 0, 0)
# define LIST_TO_SUM5(a1, a2, a3, a4, a5) LIST_TO_SUM8(a1, a2, a3, a4, a5, 0, 0, 0)
# define LIST_TO_SUM6(a1, a2, a3, a4, a5, a6) LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, 0, 0)
# define LIST_TO_SUM7(a1, a2, a3, a4, a5, a6, a7) LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, a7, 0)
# define LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, a7, a8)
DO_ ## a1(X, 1)
DO_ ## a2(X, (1+ ## a1 ))
DO_ ## a3(X, (1+ ## a1 + ## a2))
DO_ ## a4(X, (1+ ## a1 + ## a2 + ## a3))
DO_ ## a5(X, (1+ ## a1 + ## a2 + ## a3 + ## a4))
DO_ ## a6(X, (1+ ## a1 + ## a2 + ## a3 + ## a4 + ## a5))
DO_ ## a7(X, (1+ ## a1 + ## a2 + ## a3 + ## a4 + ## a5 + ## a6))
DO_ ## a8(X, (1+ ## a1 + ## a2 + ## a3 + ## a4 + ## a5 + ## a6 + ## a7))
# define LIST_TO_SUM(num, ...) LIST_TO_SUM ## num ( __VA_ARGS__ )
# define INIT_ARRAY_WITH_MACRO(mac) { mac }
#endif
// Define a template meta program to demostrate its usage to initialize an array
template <int n>
struct Fib {
enum { value = (Fib<n-1>::value + Fib<n-2>::value) };
};
template <>
struct Fib<1> {
enum { value = 1 };
};
template <>
struct Fib<0> {
enum { value = 0 };
};
//Utility macro to display the array and its size
#define DISPLAY_ARRAY(name, cols)
std::cout << "Array: " #name "[" << (sizeof(name)/sizeof(int)) << "] =n";
for (int i = 0; i < sizeof(name)/sizeof(int); i++) {
std::cout << name[i] << ((i%cols)==(cols-1) ? "n" : ", t");
}
std::cout << std::endl;
int main() {
//Create an array with 100 elements such that each element equals the square of its index
#define X(n) (n) * (n),
int aSqrs[100] = INIT_ARRAY_WITH_MACRO( LIST_TO_SUM(3, 64, 32, 4) );
#undef X
//Create an array of the first 14 fibonacci numbers, use the sum of seven 2's just for the heck of it.
//This uses a template meta-program to generate the fibonacci numbers
#define X(n) Fib<n>::value,
int aFibs[] = INIT_ARRAY_WITH_MACRO( LIST_TO_SUM(7, 2,2,2,2,2,2,2) );
#undef X
//Display our two arrays to check the content.
DISPLAY_ARRAY(aSqrs, 10);
DISPLAY_ARRAY(aFibs, 7);
//Create an integer that is the sum of the first 14 elements of aFibs
#define X(n) + aFibs[(n) - 1]
int sum = 0 + LIST_TO_SUM(3, 8, 4, 2);
#undef X
std::cout << "Sum of first 14 Fibonacci Numbers is: " << sum << std::endl;
return 0;
}
0 Replies - 75 Views - Last Post: 07 June 2009 - 10:00 PM
#1
NickDMax
- Can grep dead trees!
-
Reputation: 2255
- Posts: 9,245
- Joined: 18-February 07
Preprocessor Initialize Arrays II
Posted 07 June 2009 - 10:00 PM
Description: This snippet uses an X-macro so you must define the macro X taking 1 argument before you can use the LIST_TO_SUM(num, ...) macro. In the LIST_TO_SUM(num, ...) macro the num is the number of arguments that follow. This can create a sum of any power of 2 up to 128, using 8 numbers. See the main() function for usage.Demonstrates another way to use the preprocessor to initialize arrays at compile time.
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MultiQuoteReplies To: Preprocessor Initialize Arrays II
#2
NickDMax
- Can grep dead trees!
-
Reputation: 2255
- Posts: 9,245
- Joined: 18-February 07
Re: Preprocessor Initialize Arrays II
Posted 07 June 2009 - 10:00 PM
Description: This snippet uses an X-macro so you must define the macro X taking 1 argument before you can use the LIST_TO_SUM(num, ...) macro. In the LIST_TO_SUM(num, ...) macro the num is the number of arguments that follow. This can create a sum of any power of 2 up to 128, using 8 numbers. See the main() function for usage.Demonstrates another way to use the preprocessor to initialize arrays at compile time.
#include <iostream>
#ifndef INIT_ARRAY_WITH_MACRO
//The DO_# Macros will do a particular macro m a given number of times.
// the argument n keeps track of now many times..
// note n starts at 1 (as apposed to 0 which might seem natural).
# define DO_0(m, n)
# define DO_1(m, n) m((n))
# define DO_2(m, n) DO_1(m, n) DO_1(m, (n+1))
# define DO_4(m, n) DO_2(m, n) DO_2(m, (n+2))
# define DO_8(m, n) DO_4(m, n) DO_4(m, (n+4))
# define DO_16(m, n) DO_8(m, n) DO_8(m, (n+8))
# define DO_32(m, n) DO_16(m, n) DO_16(m, (n+16))
# define DO_64(m, n) DO_32(m, n) DO_32(m, (n+32))
# define DO_128(m, n) DO_64(m, n) DO_64(m, (n+64))
//These macros will preform the X macro N times where N = Sum(a1...a8)
// note that a1-a8 must be powers of 2
# define LIST_TO_SUM1(a1) LIST_TO_SUM8(a1, 0, 0, 0, 0, 0, 0, 0)
# define LIST_TO_SUM2(a1, a2) LIST_TO_SUM8(a1, a2, 0, 0, 0, 0, 0, 0)
# define LIST_TO_SUM3(a1, a2, a3) LIST_TO_SUM8(a1, a2, a3, 0, 0, 0, 0, 0)
# define LIST_TO_SUM4(a1, a2, a3, a4) LIST_TO_SUM8(a1, a2, a3, a4, 0, 0, 0, 0)
# define LIST_TO_SUM5(a1, a2, a3, a4, a5) LIST_TO_SUM8(a1, a2, a3, a4, a5, 0, 0, 0)
# define LIST_TO_SUM6(a1, a2, a3, a4, a5, a6) LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, 0, 0)
# define LIST_TO_SUM7(a1, a2, a3, a4, a5, a6, a7) LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, a7, 0)
# define LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, a7, a8)
DO_ ## a1(X, 1)
DO_ ## a2(X, (1+ ## a1 ))
DO_ ## a3(X, (1+ ## a1 + ## a2))
DO_ ## a4(X, (1+ ## a1 + ## a2 + ## a3))
DO_ ## a5(X, (1+ ## a1 + ## a2 + ## a3 + ## a4))
DO_ ## a6(X, (1+ ## a1 + ## a2 + ## a3 + ## a4 + ## a5))
DO_ ## a7(X, (1+ ## a1 + ## a2 + ## a3 + ## a4 + ## a5 + ## a6))
DO_ ## a8(X, (1+ ## a1 + ## a2 + ## a3 + ## a4 + ## a5 + ## a6 + ## a7))
//This will simplify the process by using an arbitrary number of arguments given by num
// Note that this still must be between 1 and 8 arguments
# define LIST_TO_SUM(num, ...) LIST_TO_SUM ## num ( __VA_ARGS__ )
# define INIT_ARRAY_WITH_MACRO(mac) { mac }
#endif
// Define a template meta program to demostrate its usage to initialize an array
template <int n>
struct Fib {
enum { value = (Fib<n-1>::value + Fib<n-2>::value) };
};
template <>
struct Fib<1> {
enum { value = 1 };
};
template <>
struct Fib<0> {
enum { value = 0 };
};
//Utility macro to display the array and its size
#define DISPLAY_ARRAY(name, cols)
std::cout << "Array: " #name "[" << (sizeof(name)/sizeof(int)) << "] =n";
for (int i = 0; i < sizeof(name)/sizeof(int); i++) {
std::cout << name[i] << ((i%cols)==(cols-1) ? "n" : ", t");
}
std::cout << std::endl;
int main() {
//Create an array with 100 elements such that each element equals the square of its index
#define X(n) (n) * (n),
int aSqrs[100] = INIT_ARRAY_WITH_MACRO( LIST_TO_SUM(3, 64, 32, 4) );
#undef X
//Create an array of the first 14 fibonacci numbers, use the sum of seven 2's just for the heck of it.
//This uses a template meta-program to generate the fibonacci numbers
#define X(n) Fib<n>::value,
int aFibs[] = INIT_ARRAY_WITH_MACRO( LIST_TO_SUM(7, 2,2,2,2,2,2,2) );
#undef X
//Display our two arrays to check the content.
DISPLAY_ARRAY(aSqrs, 10);
DISPLAY_ARRAY(aFibs, 7);
//Create an integer that is the sum of the first 14 elements of aFibs
#define X(n) + aFibs[(n) - 1]
int sum = 0 + LIST_TO_SUM(3, 8, 4, 2);
#undef X
std::cout << "Sum of first 14 Fibonacci Numbers is: " << sum << std::endl;
return 0;
}
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#3
NickDMax
- Can grep dead trees!
-
Reputation: 2255
- Posts: 9,245
- Joined: 18-February 07
Re: Preprocessor Initialize Arrays II
Posted 07 June 2009 - 10:00 PM
Description: This snippet uses an X-macro so you must define the macro X taking 1 argument before you can use the LIST_TO_SUM(num, ...) macro. In the LIST_TO_SUM(num, ...) macro the num is the number of arguments that follow. This can create a sum of any power of 2 up to 128, using 8 numbers. See the main() function for usage.Demonstrates another way to use the preprocessor to initialize arrays at compile time.
#include <iostream>
#ifndef INIT_ARRAY_WITH_MACRO
//The DO_# Macros will do a particular macro m a given number of times.
// the argument n keeps track of now many times..
// note n starts at 1 (as apposed to 0 which might seem natural).
# define DO_0(m, n)
# define DO_1(m, n) m((n))
# define DO_2(m, n) DO_1(m, n) DO_1(m, (n+1))
# define DO_4(m, n) DO_2(m, n) DO_2(m, (n+2))
# define DO_8(m, n) DO_4(m, n) DO_4(m, (n+4))
# define DO_16(m, n) DO_8(m, n) DO_8(m, (n+8))
# define DO_32(m, n) DO_16(m, n) DO_16(m, (n+16))
# define DO_64(m, n) DO_32(m, n) DO_32(m, (n+32))
# define DO_128(m, n) DO_64(m, n) DO_64(m, (n+64))
//These macros will preform the X macro N times where N = Sum(a1...a8)
// note that a1-a8 must be powers of 2
# define LIST_TO_SUM1(a1) LIST_TO_SUM8(a1, 0, 0, 0, 0, 0, 0, 0)
# define LIST_TO_SUM2(a1, a2) LIST_TO_SUM8(a1, a2, 0, 0, 0, 0, 0, 0)
# define LIST_TO_SUM3(a1, a2, a3) LIST_TO_SUM8(a1, a2, a3, 0, 0, 0, 0, 0)
# define LIST_TO_SUM4(a1, a2, a3, a4) LIST_TO_SUM8(a1, a2, a3, a4, 0, 0, 0, 0)
# define LIST_TO_SUM5(a1, a2, a3, a4, a5) LIST_TO_SUM8(a1, a2, a3, a4, a5, 0, 0, 0)
# define LIST_TO_SUM6(a1, a2, a3, a4, a5, a6) LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, 0, 0)
# define LIST_TO_SUM7(a1, a2, a3, a4, a5, a6, a7) LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, a7, 0)
# define LIST_TO_SUM8(a1, a2, a3, a4, a5, a6, a7, a8)
DO_ ## a1(X, 1)
DO_ ## a2(X, (1 + a1 ))
DO_ ## a3(X, (1 + a1 + a2))
DO_ ## a4(X, (1 + a1 + a2 + a3))
DO_ ## a5(X, (1 + a1 + a2 + a3 + a4))
DO_ ## a6(X, (1 + a1 + a2 + a3 + a4 + a5))
DO_ ## a7(X, (1 + a1 + a2 + a3 + a4 + a5 + a6))
DO_ ## a8(X, (1 + a1 + a2 + a3 + a4 + a5 + a6 + a7))
//This will simplify the process by using an arbitrary number of arguments given by num
// Note that this still must be between 1 and 8 arguments
# define LIST_TO_SUM(num, ...) LIST_TO_SUM ## num ( __VA_ARGS__ )
# define INIT_ARRAY_WITH_MACRO(mac) { mac }
#endif
// Define a template meta program to demostrate its usage to initialize an array
template <int n>
struct Fib {
enum { value = (Fib<n-1>::value + Fib<n-2>::value) };
};
template <>
struct Fib<1> {
enum { value = 1 };
};
template <>
struct Fib<0> {
enum { value = 0 };
};
//Utility macro to display the array and its size
#define DISPLAY_ARRAY(name, cols)
std::cout << "Array: " #name "[" << (sizeof(name)/sizeof(int)) << "] =n";
for (int i = 0; i < sizeof(name)/sizeof(int); i++) {
std::cout << name[i] << ((i%cols)==(cols-1) ? "n" : ", t");
}
std::cout << std::endl;
int main() {
//Create an array with 100 elements such that each element equals the square of its index
#define X(n) (n) * (n),
int aSqrs[100] = INIT_ARRAY_WITH_MACRO( LIST_TO_SUM(3, 64, 32, 4) );
#undef X
//Create an array of the first 14 fibonacci numbers, use the sum of seven 2's just for the heck of it.
//This uses a template meta-program to generate the fibonacci numbers
#define X(n) Fib<n>::value,
int aFibs[] = INIT_ARRAY_WITH_MACRO( LIST_TO_SUM(7, 2,2,2,2,2,2,2) );
#undef X
//Display our two arrays to check the content.
DISPLAY_ARRAY(aSqrs, 10);
DISPLAY_ARRAY(aFibs, 7);
//Create an integer that is the sum of the first 14 elements of aFibs
#define X(n) + aFibs[(n) - 1]
int sum = 0 + LIST_TO_SUM(3, 8, 4, 2);
#undef X
std::cout << "Sum of first 14 Fibonacci Numbers is: " << sum << std::endl;
return 0;
}
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