Homework #7 – Fun with Strings and Vectors

hw7.cpp

#include <iostream>
using std::cout;
using std::endl;

#include <cstdlib>

#include "StringUtility.h"
using namespace JulesBaratoux;


int main(int argc, const char *argv[])
{
	StringUtility::tests::join();
	StringUtility::tests::reverse();
	StringUtility::tests::combine();
	StringUtility::tests::leftPad();
	return EXIT_SUCCESS;
}

StringUtility.cpp

#include <iostream>
using std::cout;
using std::endl;
using std::ostream;

#include <string>
using std::string;

#include <vector>
using std::vector;

#include <algorithm>

#include <cassert>

#include "StringUtility.h"
using namespace JulesBaratoux;

// ----------------------------------------------------------------------------
ostream& JulesBaratoux::operator<< (ostream& out, const vector<string>& strings)
{
	vector<string>::size_type i = 0;
	const auto              max = strings.size() - 1;

	out << OSTREAM_START;
	while (i < max)
	{
		out << strings[i] << OSTREAM_SEP;
		++i;
	}
	return out << strings[i] << OSTREAM_END;
}


// ----------------------------------------------------------------------------
string StringUtility::join(const vector<string> & strings, char delimiter)
{
	const auto end = strings.cend() - 1;
	auto        it = strings.cbegin();

	string result;

	while (it != end)
	{
		result += *it + delimiter;
		++it;
	}

	result += *it;
	return result;
}

void StringUtility::tests::join()
{
	// Example
	const string expected = "abc*def*ghi";

	assert(StringUtility::join({"abc", "def", "ghi"}, '*') == expected);

	// Question 6
	cout << StringUtility::join({"The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"}, ',') << endl;
}

// ----------------------------------------------------------------------------
vector<string> StringUtility::reverse(const vector<string>& strings)
{
	auto reversed(strings);

	std::reverse(reversed.begin(), reversed.end());

	for (auto& str : reversed)
	{
			std::reverse(str.begin(), str.end());
	}

	return reversed;
}

void StringUtility::tests::reverse()
{
	// Example
	const vector<string> expected{{"ihg", "fed", "cba"}};

	assert(StringUtility::reverse( {"abc", "def", "ghi"} ) == expected);

	// Question 7
	cout << StringUtility::reverse( {"The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"} ) << endl;
}

// ----------------------------------------------------------------------------
vector<string> StringUtility::combine(const vector<string>& left, const vector<string>& right)
{
	vector<string> combined;

	combined.reserve(left.size() * right.size());

	for (const auto& left_string : left)
	{
		for (const auto& right_string : right)
		{
			combined.push_back(left_string + right_string);
		}
	}

	return combined;
}

void StringUtility::tests::combine()
{
	// Example
	const vector<string>     left = {"ab",   "cd",   "ef"};
	const vector<string>    right = {"gh",   "ij",   "kl"};
	const vector<string> expected = {"abgh", "abij", "abkl",
	                                 "cdgh", "cdij", "cdkl",
	                                 "efgh", "efij", "efkl"};

	assert(StringUtility::combine(left, right) == expected);

	// Question 8
	cout << StringUtility::combine({"Mr.", "Mrs."}, {"Jones", "Smith", "Williams"}) << endl;
}

// ----------------------------------------------------------------------------
vector<string> StringUtility::leftPad(const vector<string>& strings, char pad)
{
	string::size_type size = 0;
	vector<string>  padded(strings);

	for (const auto& str : strings)
	{
		if (str.size() > size)
		{
			size = str.size();
		}
	}

	for (auto& str : padded)
	{
		str.insert(0, size - str.size(), pad);
	}

	return padded;
}

void StringUtility::tests::leftPad()
{
	// Example
	const vector<string> expected {{"**a", "*bb", "ccc"}};

	assert(StringUtility::leftPad({"a", "bb", "ccc"}, '*') == expected);

	// Question 9
	cout << StringUtility::leftPad({"The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"}, '*') << endl;
}

StringUtility.h

#pragma once

#include <ostream>
using std::ostream;

#include <string>
using std::string;

#include <vector>
using std::vector;

namespace JulesBaratoux
{
    	static constexpr auto OSTREAM_START = "[";
	static constexpr auto OSTREAM_END   = "]";
	static constexpr auto OSTREAM_SEP   = ", ";

	ostream& operator<< (ostream& out, const vector<string>& strings);

struct StringUtility
{
	// Concatenate strings from the strings parameter together placing the
	// delimiter character in between each pair of strings. The resulting string
	// is returned.
	static string join(const vector<string> & strings, char delimiter);

	// Return a vector containing the strings from the strings parameter in
	// reversed order and with the contents of each string reversed.
	static vector<string> reverse(const vector<string>& strings);

	// Returns a vector containing every string from left concatenated with
	// every string from right.
	static vector<string> combine(const vector<string>& left, const vector<string>& right);

	// Returns a vector containing each string from the strings parameter
	// left-padded with the pad character so that each resulting string has
	// a length equal to the longest original string.
	static vector<string> leftPad(const vector<string>& strings, char pad);

	struct tests
	{
		static void join();
		static void reverse();
		static void combine();
		static void leftPad();
	};

	friend tests;
};

}