What do these warnings mean?

[Ch1156]

Here is my code:

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

using namespace std;

void encrypt()
{
    ifstream fIn;
    ifstream passIn;
    string file_name2;
    string store_text2;
    char lower[27] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','\0'};
    char upper[27] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','\0'};
    char replace[28] = {'♎','×','♋','¼','Ѝ','☩','þ','ß','¤','Œ','Ø','★','유','½','å','¹','°','Ä','@','¡','♯','^','','♚','*','™','✝','\0'};
    char upperReplace[28] = {'³','²','µ','÷','û','ê','ì','Ñ','Д','Ó','Ö','É','п','⅞','Á','¦','Ü','Û','Ù','Õ','я','Ю','Ã','Ш','₧','Æ','✝','\0'};
    char space = ' ';
    int pos = string::npos;

    cin.ignore(100, '\n');

    cout << "What is the exact name of the file for encryption" << endl;
    getline(cin, file_name2);

    fIn.open(file_name2.c_str());

    stringstream ss(stringstream::in | stringstream::app | stringstream::out);

    while(getline(fIn, store_text2))
    {
        ss << store_text2 << endl;
    }

    store_text2 = ss.str();


    //Find lower case alphabet
    for(int i = 0; i < 27; i++)
    {
        while((pos = store_text2.find(lower[i])) != string::npos)
        {
            store_text2[pos] = replace[i];
        }

        while((pos = store_text2.find(upper[i])) != string::npos)
        {
            store_text2[pos] = upperReplace[i];
        }

        while((pos = store_text2.find(space)) != string::npos)
        {
            store_text2[pos] = replace[27];
        }
    }

    ofstream fOut;

    fOut.open(file_name2.c_str());

    fOut << store_text2;

    cout << "File Encrypted\n" << endl;

    cout << store_text2;

    fOut.close();

    cin.sync();
    cin.get();
}


void decrypt()
{
    ifstream fIn;
    string file_name;
    char space = ' ';
    string store_text;
    char lower[27] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','\0'};
    char upper[27] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','\0'};
    char replace[28] = {'♎','×','♋','¼','Ѝ','☩','þ','ß','¤','Œ','Ø','★','유','½','å','¹','°','Ä','@','¡','♯','^','','♚','*','™','✝','\0'};
    char upperReplace[28] = {'³','²','µ','÷','û','ê','ì','Ñ','Д','Ó','Ö','É','п','⅞','Á','¦','Ü','Û','Ù','Õ','я','Ю','Ã','Ш','₧','Æ','✝','\0'};
    int pos = string::npos;

    cin.ignore(100, '\n');

    cout << "What is the exact name of the file for decryption" << endl;
    getline(cin, file_name);

    fIn.open(file_name.c_str());

    stringstream ss(stringstream::in | stringstream::app | stringstream::out);

    while(getline(fIn, store_text))
    {
        ss << store_text << endl;
    }

    store_text = ss.str();


    for(int i = 0; i < 27; i++)
    {
        while((pos = store_text.find(replace[i])) != string::npos)
        {
            store_text[pos] = lower[i];
        }

        while((pos = store_text.find(upperReplace[i])) != string::npos)
        {
            store_text[pos] = upper[i];
        }

        while((pos = store_text.find(replace[27])) != string::npos)
        {
            store_text[pos] = space;
        }
    }

    ofstream fOut2;

    fOut2.open(file_name.c_str());

    fOut2 << store_text;

    cout << "File Decrypted\n" << endl;

    cout << store_text;

    fOut2.close();

    cin.sync();
    cin.get();
}


int password()
{
    string newPassword;
    string existingPassword;
    string store;
    bool passwordCreated;
    ifstream passIn;
    ofstream passOut;

    passIn.open("PassKey.txt");

    passIn >> passwordCreated;

    while(getline(passIn, store))
    {
        newPassword = store;
    }

    if(passwordCreated == 1)
    {
        passIn >> passwordCreated;

        cout << "Please enter your password" << endl;
        getline(cin, existingPassword);

            if(newPassword != existingPassword)
            {
                cout << "Incorrect password" << endl;
                cin.get();
                return 0;
            }
            else if(newPassword == existingPassword)
            {
                cout << "Correct password, Proceed" << endl;
                return 1;
            }
    }

    passOut.open("PassKey.txt");
    passOut << passwordCreated << endl;
    passOut << newPassword << endl;

    //If password is not set up yet, create one

    if(passwordCreated == 0)
    {
        passOut.close();
        passOut.open("PassKey.txt");
        cout << "Please create a password" << endl;

        do
        {
            getline(cin, newPassword);

            if(newPassword.length() <= 4)
            {
                cout << "Your password must be more than 4 characters long!!\n" << endl;
            }
        }
        while(newPassword.length() <= 4);

        if(newPassword.length() > 4)
        {
            passOut << true << endl;
            passOut << newPassword << endl;
            cout << "Your password is: " << newPassword << endl;
        }
        passOut.close();
    }
}


int main()
{
    if(password() == 0) return 0;

    int choice;

    cout << "\n";
    cout << "Encryptor Version 1.2.4 Alpha\n" << endl;

    cout << "What do you want to do?" << endl;
    cout << "1) Encrypt file" << endl;
    cout << "2) Decrypt file" << endl;
    cout << "3) Exit Program" << endl;

    while(choice != 3)
    {
        cin >> choice;
    }

    if(choice == 1)
    {
        encrypt();
    }
    else if(choice == 2)
    {
        decrypt();
    }
    if(choice == 3)
    {
        return 0;
    }

    return 0;
}

and here are the warnings

[Ch1156]

I had to remove some because the post was too long

||=== Encryptor, Release ===|
C:\Users\Chay\Desktop\Encryptor\main.cpp|16|warning: multi-character character constant|
C:\Users\Chay\Desktop\Encryptor\main.cpp|83|warning: multi-character character constant|
C:\Users\Chay\Desktop\Encryptor\main.cpp||In function 'void encrypt()':|
C:\Users\Chay\Desktop\Encryptor\main.cpp|16|warning: overflow in implicit constant conversion|
C:\Users\Chay\Desktop\Encryptor\main.cpp|17|warning: overflow in implicit constant conversion|
C:\Users\Chay\Desktop\Encryptor\main.cpp|41|warning: comparison between signed and unsigned integer expressions|
C:\Users\Chay\Desktop\Encryptor\main.cpp|46|warning: comparison between signed and unsigned integer expressions|
C:\Users\Chay\Desktop\Encryptor\main.cpp|51|warning: comparison between signed and unsigned integer expressions|
C:\Users\Chay\Desktop\Encryptor\main.cpp||In function 'void decrypt()':|
C:\Users\Chay\Desktop\Encryptor\main.cpp|82|warning: overflow in implicit constant conversion|
C:\Users\Chay\Desktop\Encryptor\main.cpp|82|warning: overflow in implicit constant conversion|
C:\Users\Chay\Desktop\Encryptor\main.cpp|82|warning: overflow in implicit constant conversion|
C:\Users\Chay\Desktop\Encryptor\main.cpp|82|warning: overflow in implicit constant conversion|
C:\Users\Chay\Desktop\Encryptor\main.cpp|105|warning: comparison between signed and unsigned integer expressions|
C:\Users\Chay\Desktop\Encryptor\main.cpp|110|warning: comparison between signed and unsigned integer expressions|
C:\Users\Chay\Desktop\Encryptor\main.cpp|115|warning: comparison between signed and unsigned integer expressions|
C:\Users\Chay\Desktop\Encryptor\main.cpp||In function 'int password()':|
C:\Users\Chay\Desktop\Encryptor\main.cpp|207|warning: control reaches end of non-void function|
||=== Build finished: 0 errors, 207 warnings ===|

how do i fix them?

[Peter87]

warning: multi-character character constant|

This happens because some of the characters you try to put into the char literal takes more than 1 byte. The result will be some implementation defined value of type int.

warning: overflow in implicit constant conversion|

You get this because you try to convert std::string::npos to an int, but npos has a too large value to be stored in an int.

warning: comparison between signed and unsigned integer expressions|

Make pos type std::size_t or std::string::size_type and you will get rid of this and the previous warning.

[Ch1156]

ok i did size_t pos = string::npos; for both functions and i still get like 200 warnings, do i need to change the chars?

[newbieg]

If you are really set on using those replacement characters then you might have to use wchar_t also known as wide characters, I don't use CLR/CLI but look these up on this site and you'll get some pretty good examples.

[Ch1156]

that fiex quite a bit, i had 201 warnings now i only have 127. and now i get a bunch of these errors

warning: large integer implicitly truncated to unsigned type
warning: multi-character character constant

[newbieg]

1. I change my suggestion, instead of using wide characters (which would mean you'd have to learn CLR/CLI, or at least look up a couple tutorials) try just making the encrypted letters regular letters that have been scrambled.


2. The while loop in main needs to enclose all of the if statements, right now it just constantly loops input without action.

3. My compiler also threw out a warning that choice wasn't initialized, so set choice equal to 0 when you first declare it.

[Peter87]

Wide character literals should be prefixed with L, L'★'. Not sure if you want to use wide characters because most text files are not stored in this format.

If the encoding being used support these characters (e.g. UTF-8) you could use strings instead. So instead of replacing characters you replace substrings.

Your encryption/decryption method is not perfect. If the file contains one of the special characters the decryption function will incorrectly convert it. E.g. if you have a file containing the text "åsna" (means donkey in Swedish). After encryption it becomes "å@½♎", and after decryption it becomes "osna" which is not the same as the original text.