Accumulate and Find_if (LAMBDA)

Thesar (30)
I am doing a program where the user chooses to create a list either with ints or doubles. The classes need therefor to be templated. In these classes i also have function to calculate the avarage, the sum and also find the first occuring value between 1500 and 1900.

But when i try to calculate the sum i only get 0, when i try to calculate avarage it crashes, when i try to find first between 1500 and 1900 it only returns a weird number

What is happening? Trying to understand Lambda

ListManipulator.hpp
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#pragma once

#include <list>
#include <random>
#include <ctime>
#include <numeric>
#include <functional>
#include <iterator>



template<typename T>
class ListManipulator {
private:
	std::list<T> *theList;

public:
	ListManipulator() { theList = new std::list<T>[20]; }
	ListManipulator(std::list<T> *aList);
	~ListManipulator() {}

	void fillList();
	T sumList() const;
	T listAverage() const;
	bool findFirst1500_1900(T &num) const;
	void divideByTwo();
	void swapPlaces();
	void findMinMax(T &min, T &max) const;
	void sortList();
	void clearList();
	std::list<T> getList() const;
	void saveToFile() const;
	void loadFromFile();
	T random1();

};



template<typename T> ListManipulator<T>::ListManipulator(std::list<T> *aList) {
	theList(aList);
}

template<typename T>
T ListManipulator<T>::random1()
{
	std::uniform_real_distribution<double> random(1000, 2000);
	std::default_random_engine generator(static_cast<unsigned>(std::time(0)));

	return random(generator);
}
// find the first occuring number with value between 1500-1900
template<typename T> 
bool ListManipulator<T> ::findFirst1500_1900(T &num) const
{
	auto it = find_if(theList->begin(), theList->end(), [num](T a) {
		return (a >= 1500 && a <= 1900); });
	return true;

		return false;
}

// fill the list with 20 random numbers
template<typename T>
void ListManipulator<T>::fillList()
{
	std::uniform_real_distribution<double> random(1000, 2000);
	std::default_random_engine generator(static_cast<unsigned>(std::time(0)));
	
	auto myGenerator = std::bind(random, generator);
	//std::generate(theList->begin(), theList->end(), myGenerator);
	
	std::generate(theList->begin(), theList->end(), myGenerator);


	/*default_random_engine randomGenerator(random_device{}());
	my_distribution<T> distribution(1000, 2000);
	auto myGenerator = bind(distribution, randomGenerator);
	generate(theList.begin(), theList.end(), myGenerator);*/
}

template<typename T>
T ListManipulator<T>::sumList() const
{
	auto first = theList->begin();
	auto last = theList->end();
T total=std::accumulate(first, last, T(0), [](T all, T each) { return all + each; });
return total;
}

template<typename T>
T ListManipulator<T>::listAverage() const
{
	auto first = theList->begin();
	auto last = theList->end();
	return std::accumulate(first, last, T(0)) / theList->size();
}

UserInterface.hpp
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#pragma once

// include the appropriate header and define the clearScr and Sleep functions depending on platform used
#if defined __WIN32__ || defined _WIN32
#include <windows.h>
#define clearScr() system("cls")
#else 
#include <unistd.h>
#define Sleep(x) usleep((x)*1000)
#define clearScr() printf("\033[H\033[J")
#endif

#include "ListManipulator.hpp"
#include <memory>
#include <list>
#include <iostream>
#include <string>
#include <iomanip>


template<typename T>
class UserInterface
{
private:
ListManipulator<T> *myList;
T minValue;
T maxValue;
bool done;
	
public:

	UserInterface() : minValue(0), maxValue(0), done(true) { myList = new ListManipulator<T>; }
	~UserInterface(){}


	bool chooseList();
	void runPro();
	void getMinMax();
	void fillList();
	void menu();
	void choice();
	void first1500_1900();

	
};

void goOn(const std::string &message);
void clearScreen();





using namespace std;

void goOn(const std::string &message)
{
	std::cout << message << std::endl;
	std::cin.get();
}

void clearScreen() {

	clearScr();
}


template<typename T>
bool UserInterface<T>::chooseList() {
	std::list<int> *intList;
	std::list<double> *doubleList;
	int choice;
	std::cout << "Choose type of list." << std::endl
		<< "1. Int." << std::endl
		<< "2. Double." << std::endl;

	std::cin >> choice;
	std::cin.get();

	switch (choice) {

	case 1: return true;
		break;
	case 2: return false;
		break;
	}

}

template<typename T>
void UserInterface<T>::menu() {

	std::cout << "##### MENU #####" << std::endl
		<< "1. Fill list" << std::endl
		<< "2. Summerize list" << std::endl
		<< "3. Average value" << std::endl
		<< "4. Find first number between 1500-1900" << std::endl
		<< "5. Divied by two" << std::endl
		<< "6. Swap places" << std::endl
		<< "7. Find Min and Max" << std::endl
		<< "8. Sort" << std::endl
		<< "9. Clear list" << std::endl
		<< "10. Write to file" << std::endl
		<< "11. Load from file" << std::endl
		<< "12. Print list" << std::endl
		<< "13. Quit" << std::endl;
}

template<typename T>
void UserInterface<T>::choice()
{
	int choice;
	std::cout << "My choice: " << flush;
	std::cin >> choice;
	std::cin.get();

	switch (choice) {

	case 1: fillList();
		break;
	case 2: std::cout << "The sum is: " << myList->sumList() << std::endl;
		goOn("Press enter for main menu...");
		break;
	case 3: std::cout << "The avarage is: " << myList->listAverage() << std::endl;
		goOn("Press enter for main menu...");
		break;
	case 4: first1500_1900();
	case 13: done = false;
		break;
	}
}

void chooseType()
{


}

template<typename T> void UserInterface<T>::runPro()
{
	while (done) {
		clearScreen();
		menu();
		choice();
	}

}

template<typename T> void UserInterface<T>::first1500_1900()
{
	T e;
		if (myList->findFirst1500_1900(e))
			std::cout << "First between 1500-1900 is: " << e << std::endl;
		else
			std::cout << "No number between 1500-1900" << std::endl;
		goOn("Press enter for main menu...");
}

template<typename T> void UserInterface<T>::getMinMax()
{
	myList.FindMinMax(minValue, maxValue);
	std::cout << "Min value is: " << minValue << std::endl
		<< "Max value is: " << maxValue << std::endl;
	goOn("Press enter for main menu...");
}

template<typename T> void UserInterface<T>::fillList()
{
	clearScreen();
	myList->fillList();
	std::cout << "The list has been filled with 20 numbers." << std::endl;
	goOn("Press enter for main menu...");
}

main.cpp
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#include "UserInterface.hpp"
#include <iostream>


int main() {
	bool looping = true;

	while (looping) {
		int choice;
		std::cout << "Choose type of list." << std::endl
			<< "1. Int." << std::endl
			<< "2. Double." << std::endl;

		std::cin >> choice;
		std::cin.get();
		if (choice == 1) {
			UserInterface<int> finalUI;
			finalUI.runPro();
		
		}
		else if (choice == 2) {
			UserInterface<float> finalUI;
			finalUI.runPro();
		
		}
		else
			std::cout << "Please choose an option between 1 and 2" << std::endl;
	}


}
tpb (1495)
You seem to be expecting num to magically get a value in findFirst1500_1900. Try something like this (untested and I've only taken a very quick look at your code).
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template<typename T> 
bool ListManipulator<T>::findFirst1500_1900(T &num) const {
	auto it = find_if(theList->begin(), theList->end(), [](T a) {
		return (a >= 1500 && a <= 1900); });
	if (it != theList->end()) {
	    num = *it;
	    return true;
	}
	return false;
}

closed account (SECMoG1T)
hello i haven't read through your code but from a glance one bug stands out.

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std::list<T> *theList;//from the way you call fillist and sumlist i assume you want theList
     ///to point to a list of T elements

theList = new std::list<T>[20];///instead you creating an array of 20 such lists

theList = new std::list<T>(20);//maybe this is what you intended, 20 elements of type T
tpb (1495)
You fillList function does nothing. Look at this line:
 
 
	std::generate(theList->begin(), theList->end(), myGenerator);

You are asking it to go from begin() to end(), which is...what? The list is empty. So it does nothing.
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