count_if and for_each

[mickey]

Hello,

I need to do something like this (that doens't compile); but anyway It's a bit wrong:

class Gene {	
	char _allele;
       char getAllele() { return _allele; }
...................................
class Chromosome {
	static const int _length = 5;
	vector<Gene> _reppresentation;
       vector<Gene>& getReppresentation() { return _reppresentation; }
..........................................
 
class Population {
public:
	vector<Chromosome> _chsome;
	void computeFitnesses() {
		//ni is wrong; I need something like a vector<int> to store every;
		int ni = std::for_each( _chsome.begin(), _chsome.end(), Fitness() ).getCount();
	}
 
	class Fitness {
		Gene _g;
		int _count;
	public:
		Fitness() { }
		void operator()(Chromosome g) {
			_count = std::count_if( g.getReppresentation().begin(), g.getReppresentation().end(), fitness); //it doens't compile here on 'fitness'
 
		}
		bool fitness() { return  _g.getAllele() == '1'; } 
		int getCount() { return _count; }
	};

class Gene {	
	char _allele;
       char getAllele() { return _allele; }
...................................
class Chromosome {
	static const int _length = 5;
	vector<Gene> _reppresentation;
       vector<Gene>& getReppresentation() { return _reppresentation; }
..........................................

class Population {
public:
	vector<Chromosome> _chsome;
	void computeFitnesses() {
		//ni is wrong; I need something like a vector<int> to store every;
		int ni = std::for_each( _chsome.begin(), _chsome.end(), Fitness() ).getCount();
	}

	class Fitness {
		Gene _g;
		int _count;
	public:
		Fitness() { }
		void operator()(Chromosome g) {
			_count = std::count_if( g.getReppresentation().begin(), g.getReppresentation().end(), fitness); //it doens't compile here on 'fitness'
		
		}
		bool fitness() { return  _g.getAllele() == '1'; } 
		int getCount() { return _count; }
	};

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For each chromosome I need to return the number of '1'. Any helps, please?

[fullmetalcoder]

count_if takes a predicate as third argument, i.e a function that takes one argument (object to be checked) and the function you supply does not take any argument. Also if the fitness is a fixed value (1 in your example) you can directly use that value instead of a predicate function.

could you explain what's wrong with foreach ?

last, but not least there is a small syntax error (not in the C++ code but in the english names : it's representation not reppresentation).

[wysota]

fitness() should probably be either a function or a static method. Or you can run a simple for loop instead of that silly count_if. It completely doesn't make sense to use it here.