Name Scrambler and Selecter

[Tiidriioblaan]

I am doing a side project for a class, and what I want to do is read a random name using getline(), then put that name into a new text file, then choose a random name from the second text file.

I thought a good way to do this would be read from the first file, store it into the second, then replace the name in the first file with a blank line, or \n.

I can't figure out how to replace the name in the first file so that it doesn't repeat names on the second.

Here's the current code.

#include <iostream>
#include <string>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <ctime>

int main()
{
	std::string name;
	int name_num=0;
	std::ofstream newfile;
	std::ifstream file;
	std::ofstream rewrite;
	std::string newline = "\n";
	int* store;
	int second_name;
working:
	file.open("Names.ycl");
	while (!file.eof())
	{
		getline(std::cin, name);
		if (file.eof())
		{
			break;
		}
		name_num += 1;
                //This counts the number of names in the list
	}
	file.close();
	
	store = new int[name_num];
	second_name = name_num;
	for (int c = 0; c < name_num; c++)
	{
		//goto finish
	}

	srand(time(NULL) + (time(NULL) / 2));
	int name_choice = (rand() % name_num);
	
	newfile.open("ScrambledNames.ycl");
	file.open("Names.ycl");
	while (!file.eof())
	{
		getline(std::cin, name);
		if (file.eof())
		{
			break;
		}
		if (name_choice == name_num)
		{
			newfile << name << "\n";
			name_num = 0;
			name_choice = 0;
		}
	}
	file.close();
	newfile.close();

	finish:
}

[cire]

Rather strange requirements. In general, you need to read in the file, modify what you want, and then rewrite the entire file when you update a file.

// caveat: untested
#include <cstdlib>
#include <ctime>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>

std::vector<std::string> readFile(const std::string& name) 
{
    std::vector<std::string> result;
    std::string line;

    std::ifstream in(name);
    while (getline(in, line))
        result.push_back(line);
    
    return result;
}

void updateFile(const std::string& name, const std::vector<std::string>& names)
{
    std::ofstream out(name);
    for (auto& n : names)
        out << n << '\n';
}

void appendToFile(const std::string& fname, const std::string & name)
{
    std::ofstream out(fname, std::ios::app);
    out << name << '\n';
}

std::vector<std::string>::iterator getRandomElement(std::vector<std::string>& v)
{
    return v.begin() + rand() % v.size();
}

std::string removeRandomElement(std::vector<std::string> & v)
{
    auto it = getRandomElement(v);
    auto result = std::move(*it);
    v.erase(it);
    return result;
}


int main()
{
    std::srand(std::time(0));

    const std::string sourceFile = "Names.ycl";
    const std::string targetFile = "ScrambledNames.ycl";

    auto names = readFile(sourceFile);
    appendToFile(targetFile, removeRandomElement(names));
    updateFile(sourceFile, names);

    names.clear();
    names = readFile(targetFile);
    auto randomName = *getRandomElement(names);

    std::cout << randomName << '\n';
}

[Tiidriioblaan]

Running your code, I got a compile error, integer division by zero.

This was the cause:

std::vector<std::string>::iterator getRandomElement(std::vector<std::string>& v)
{
	return v.begin() + rand() % v.size();
}

[cire]

Running your code, I got a compile error, integer division by zero.

That's not a compile error. This would happen if v had size 0, and v would have size 0 if readFile failed to read from the file.

[Tiidriioblaan]

Ah, forgot about that.

It works perfectly, now that I've added the files being read and written to.
Thanks!