Thread: Automatic Counting

Referring to - http://www.codeguru.com/cpp/tic/tic0113.shtml

Code:

//: C10:StaticArray.cpp
// Initializing static arrays

class Values {
  // static consts can be initialized in-place:
  static const int scSize = 100;
  // Automatic counting works with static consts:
  static const float scTable[] = {
    1.1, 2.2, 3.3, 4.4
  };
  static const char scLetters[] = {
    'a', 'b', 'c', 'd', 'e',
    'f', 'g', 'h', 'i', 'j'
  };
  // Non-const statics must be 
  // initialized externally:
  static int size;
  static float table[4];
  static char letters[10];
};

int Values::size = 100;

float Values::table[4] = {
  1.1, 2.2, 3.3, 4.4
};

char Values::letters[10] = {
  'a', 'b', 'c', 'd', 'e',
  'f', 'g', 'h', 'i', 'j'
};

int main() { Values v; } ///:~

Automatic counting works with static consts: - what is automatic counting?

but you cannot use automatic counting for non- static const arrays - explaination?

>> what is automatic counting?
Notice that there is no size specified for that array. The compiler automatically counts the values in the initializer and uses that for the size.

>> explaination
The compiler must have enough knowledge about the class to create an object by the end of the class definition, including the exact sizes of all the components. So you have to provide a size inside the class declaration for a non-static array, even if it is const.

Code:

#include<iostream>
using namespace std;

class Values 
{
  static const int scSize = 100;
  static const float scTable[] = {1.1, 2.2, 3.3, 4.4 };
  static const char scLetters[] = {'a', 'b', 'c', 'd', 'e','f', 'g', 'h', 'i', 'j'};

  static int size;
  static float table[4];
  static char letters[10];
};

int Values::size = 100;

float Values::table[4] = {1.1, 2.2, 3.3, 4.4};

char Values::letters[10] = {'a', 'b', 'c', 'd', 'e','f', 'g', 'h', 'i', 'j'};

int main() 
{ 
    Values v;
}

i tried to compile the above code, in the definition of static const arrays inside the class

i get error - brace enclosed initializer is not allowed here

Post the full error, including which line it refers to.

What compiler/IDE are you using?

Originally Posted by Daved

Post the full error, including which line it refers to.

What compiler/IDE are you using?

g++ test.cpp

test.cpp:7: error: a brace-enclosed initializer is not allowed here before '{' token
test.cpp:7: error: invalid in-class initialization of static data member of non-integral type `const float[]'
test.cpp:8: error: a brace-enclosed initializer is not allowed here before '{' token
test.cpp:8: error: invalid in-class initialization of static data member of non-integral type `const char[]'

using GCC/Bloodshed

I'm not sure if the codeguru page is accurate according to the standard or not. To my knowledge only integral types could be initialized in the class like that. Perhaps they use a different compiler that allows it as an extension.