Unknown Error

[SweatyCoder]

So im trying to write a program that reads the contents of two files into two separate vectors (GirlNames.txt and BoyNames.txt). Basically, I want the user to enter a boy name and a girl name and the code will judge whether or not those names are popular. I don't really understand what the error means or what to do. I was told it might be my compiler but I'm not sure. (I use Dev-C++) I tried Visual Studios but I don't understand how to use it and I think online compilers just run the code without searching through my folders for the txt files.

This is what I have so far:

#include <iostream>
#include <fstream>
#include <string>
#include <vector>

using namespace std;


vector<string> readNames(string fileName) {
    vector<string> names;
    string line;
    
    ifstream f2(fileName); // This is the line with the error
    
    while (getline (f2, line)) {
        names.push_back(line);
    }
    
    f2.close();  
    
    return names;
}

int isNamePresent(vector<string> names, string nameToCompare) {
    int result = 0;
    
    for(int i = 0; i < names.size(); i++) {
        if(names[i] == nameToCompare) {
            result = 1;
            break;
        }
    }    
    
    return result;
}

void displayResult(vector<string> names, string nameToCompare, string label) {
    if(nameToCompare != "N") {
        if(isNamePresent(names, nameToCompare) == 1)
            cout << nameToCompare << " is one of the most popular " << label << "'s names." << endl;   
        else
            cout << nameToCompare << " is not one of the most popular " << label << "'s names." << endl;    
    }
}

int main()
{
    string fileNameBoys = "BoyNames.txt";
    string fileNameGirls = "GirlNames.txt";
    
    vector<string> boyNames = readNames(fileNameBoys);

    vector<string> girlNames = readNames(fileNameGirls);
    
    string userInputBoyName, userInputGirlName;

    cout << "Enter a boy's name, or N if you do not wish to enter a boy's name: ";
    cin >> userInputBoyName;

    cout << "Enter a girl's name, or N if you do not wish to enter a girl's name: ";
    cin >> userInputGirlName;
    
    displayResult(boyNames, userInputBoyName, "boy");

    displayResult(girlNames, userInputGirlName, "girl");

    return 0;
}

This is the error I'm getting along with some other things:

(In function)
[Error] no matching function for call to 'std::basic_ifstream<char>::basic_ifstream(std::string&)'

[Note] candidates are:

(In file)
[Note] std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]

[Note] no known conversion for argument 1 from 'std::string {aka std::basic_string<char>}' to 'const char*'

[Note] std::basic_ifstream<_CharT, _Traits>::basic_ifstream() [with _CharT = char; _Traits = std::char_traits<char>]

[Note] candidate expects 0 arguments, 1 provided

[Note] std::basic_ifstream<char>::basic_ifstream(const std::basic_ifstream<char>&)

[Note] no known conversion for argument 1 from 'std::string {aka std::basic_string<char>}' to 'const std::basic_ifstream<char>&'

[Handy Andy]

Hello SweatyCoder,

It is best to copy and paste the complete error message. With out line numbers it makes it hard to figure out where you went wrong.

DEV C++ is old and outdated. Unless you know how to update the IDE to use C++11 standards you are likely to have many problems. If you need help with that I have instructions I can post.

On line 13 you define a file stream and open the file, but how do you know it opened and is usable?

Something to start on while give your code a compile.

Both MSVS 2017 Community and 2019 Community are good IDEs. Code::Blocks is also a good IDE. I use both the MSVS 2017 and 2019 versions. Like any new program it takes time to get use to.

Andy

[keskiverto]

Your error, simplified:

[Error] no matching function for call to 'std::ifstream::ifstream( std::string& )'
[Note] candidates are:
1. std::ifstream()
2. std::ifstream( const char*, std::ios_base::openmode )

[Note] no known conversion for argument 1 from 'std::string' to 'const char*'

See http://www.cplusplus.com/reference/fstream/ifstream/ifstream/

Before C++11 the std::ifstream had two constructors:

ifstream();
explicit ifstream (const char* filename, ios_base::openmode mode = ios_base::in);

Since C++11 there are four that you can use:

ifstream();
explicit ifstream (const char* filename, ios_base::openmode mode = ios_base::in);
explicit ifstream (const string& filename, ios_base::openmode mode = ios_base::in);
ifstream (ifstream&& x);

There are now two options:
1. Enable C++11 support in your compiler
2. Get data from string 'fileName' as const char*

C++11 has been around for a decade. I'd say its time to learn and use it.
There are also C++14, C++17, and C++20 so skipping the 11 could be sane.
Staying with pre-C++11 is much less so.

[Handy Andy]

Hello SweatyCoder,

I compiled your code with MSVS 2017 using the C++14 standards and had no errors. Did have 1 warning easily corrected.

Line 27 in the for loop "names.size()" returns a number of type "size_t" an "unsigned integral" type. It helps when the loop iterator matches, but not something that would stop the program from running.

After reading keskiverto's post I would agree that your DEV C++ is using pre 2011 standards. I believe the standard it starts with is 1998.

The DEV C++ that I have is version 5.11 with a build year of 2015.

To adjust the settings:
    •	Under the Tools menu choose “Compiler Options”.
    •	In the window that comes up you will see tabs for “General”, “Settings”, “Directories” and “Programs”.
    •	Choose the settings tab.
    •	In the next set of tabs that come up choose “Code Generation”.
    •	The last line should say “Language Standard (-std).
    •	On the right side of that line click on the down arrow.
    •	In the list box that comes up choose “ISO C++ 11”.
    •	Press “OK”.

This will let the IDE and compiler use the C++11 standards.

In the function "readNames" add this if statement:

ifstream f2(fileName); // This is the line with the error

if (!f2)
{
    //std::cout << "\n     File " << std::quoted(inFileName) << " did not open.\n";  // <--- Requires header file "<iomanip>".
    std::cout << "\n     File \"" << fileName << "\" did not open.\n";

    return 1;
}

The only problem is that the function needs to return an "int" not a vector. Instead you should pass the vector you need by reference, much less work this way, and use what you already have.

I will have to work on that one.

Andy

[Handy Andy]

Hello SweatyCoder,

The changes I made:

int readNames(string fileName, vector<string>& names)
{
    //vector<string> names;  // <--- Covered in the parameters.
    string line;

    ifstream f2(fileName); // This is the line with the error. You could try "filename.c_str()" for pre2011 standards.

    if (!f2)
    {
        //std::cout << "\n     File " << std::quoted(inFileName) << " did not open.\n";  // <--- Requires header file "<iomanip>".
        std::cout << "\n     File \"" << fileName << "\" did not open.\n";

        return 1;
    }

    while (getline(f2, line))
    {
        names.push_back(line);
    }

    //f2.close();  // <--- Not required as the dtor will close the file when the function looses scope.

    return 0;  // <--- Means everything worked.
}

Then in "main":

int main()
{
    const string fileNameBoys{ "BoyNames.txt" };
    const string fileNameGirls{ "GirlNames.txt" };

    int result{};
    vector<string> boyNames;
    vector<string> girlNames;

    if(result=readNames(fileNameBoys, boyNames))
       return result;

    if (result = readNames(fileNameGirls, girlNames))
        return result;

Not having any input files to use, it would help if you post the input files or at least a fair sample, so everyone would have the same files to use.

Andy

[SweatyCoder]

Thank you, all for the help I will be trying every solution. I also had no idea I was using an old version of C++. I've been using Dev C++ since high school and never had a problem with it until now. We live and we learn. Once again thank you all.