CppLearning/EssentialCpp/chap2_8.cpp

#include "utils.h"
#include <limits>
#include "chap2_8.h"

typedef vector<u32>* (*seq_ptr)(int) ;

seq_ptr seq_array[seq_cnt] = { fibon_seq };

inline bool is_size_ok(int size) {
	if (size <= 0 || size > 1024) {
		display_message("size is invalid");
		return false;
	}
	else {
		return true;
	}
}

vector<u32>* fibon_seq(int size) {
	static vector<u32> elems;

	if (!is_size_ok(size)) {
		return 0;
	}


	int current_size = elems.size();

	if (size > current_size) {
		for (int ix = current_size; ix < size; ++ix) {
			if (ix < 2) {
				elems.push_back(1);
			}
			else {
				int value_ix = elems[ix - 1] + elems[ix - 2];
				elems.push_back(value_ix);
			}

		}
	}

	return &elems;

}
/*

*/
bool fibon_elem(int position, u32& elem) {

	vector<u32>* fibon_vector = fibon_seq(position);
	if (fibon_vector) {
		elem = (*fibon_vector)[position - 1]; //index overflow
		return true;
	}
	else {
		elem = 0;
		return false;
	}

}

bool seq_elem(int position, u32& elem,
				seq_ptr seq_func) {

	if (!seq_func) {
		display_message("invalid parameter seq_func=NULL_PTR!");
		return false;
	}

	vector<u32>* vec = seq_func(position);
	if (vec) {
		elem = (*vec)[position - 1]; //index overflow
		return true;
	}
	else {
		elem = 0;
		return false;
	}

}



int main() {
	u32 elem = 0;
	bool ret = fibon_elem(0, elem);
	if (ret) {
		cout << "elem is" << elem << endl;
	}
	display_message('s');
	display_message("test string message", 1);
	display_message("test string message", 1, 2);

	string s1("test string message 1");
	vector<u32>* v1 = fibon_seq(10);
	display(*v1);

	display_message(s1, *v1);

	ret = seq_elem(100, elem, fibon_seq);

	if (ret) {
		cout << "elem is " << elem << endl;
	}

	return 0;
}