Handling Non-Ascii Chars in C++

Question

I am facing some issues with non-Ascii chars in C++. I have one file containg non-ascii chars which I am reading in C++ via file Handling. After reading the file(say 1.txt) I am storing the data into string stream and writing it into another file(say 2.txt).

Assume 1.txt contains:

ação

In 2.txt I should get same ouyput but non-Ascii chars are printed as their Hex value in 2.txt.

Also, I am quite sure that C++ is handling Ascii chars as Ascii only.

Please Help on how to print these chars correctly in 2.txt

EDIT:

Firstly Psuedo-Code for Whole Process:

1.Shell script to Read from DB one Value and stores in 11.txt
2.CPP Code(a.cpp) reading 11.txt and Writing to f.txt

Data Present in DB which is being read: Instalação

File 11.txt contains: InstalaÃ§Ã£o

File F.txt Contains: InstalaÃ§Ã£o

Ouput of a.cpp on screen: Instalação

a.cpp

#include <iterator>
#include <iostream>
#include <algorithm>
#include <sstream>
#include<fstream>
#include <iomanip>

using namespace std;
int main()
{
    ifstream myReadFile;
    ofstream f2;
    myReadFile.open("11.txt");
    f2.open("f2.txt");
    string output;
    if (myReadFile.is_open()) 
    {
        while (!myReadFile.eof())
        {
            myReadFile >> output;
                //cout<<output;

            cout<<"\n";

            std::stringstream tempDummyLineItem;
            tempDummyLineItem <<output;
            cout<<tempDummyLineItem.str();
            f2<<tempDummyLineItem.str();
        }
    }
    myReadFile.close();
    return 0;
}

Locale says this:

LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

So exactly what is your question? "How do I identify ASCII characters, and print non-ASCII as hex?" — Mats Petersson
– Mats Petersson, Commented Jul 15, 2013 at 7:37
Post your actual code (the smallest sample that exhibits your problem) and then we can tell you what minimal changes have to be made. — Qaz
– Qaz, Commented Jul 15, 2013 at 7:38
I want to get non-ascii chars printed as non-ascii only in 2.txt and not as their hex values — Mayank Jain
– Mayank Jain, Commented Jul 15, 2013 at 7:38
@chris - Sorry but I can't post actual C++ code due to copyright issues. — Mayank Jain
– Mayank Jain, Commented Jul 15, 2013 at 7:39
@MayankJain, The posted code should be about the same length as that pseudocode. There's no way that an SSCCE of this could be copyrighted. — Qaz
– Qaz, Commented Jul 15, 2013 at 7:40

Jerry Coffin · Accepted Answer · 2013-07-15 08:04:18Z

At least if I understand what you're after, I'd do something like this:

#include <iterator>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <iomanip>

std::string to_hex(char ch) {
    std::ostringstream b;
    b << "\\x" << std::setfill('0') << std::setw(2) << std::setprecision(2)
        << std::hex << static_cast<unsigned int>(ch & 0xff);
    return b.str();
}

int main(){
    // for test purposes, we'll use a stringstream for input
    std::stringstream infile("normal stuff. weird stuff:\x01\xee:back to normal");

    infile << std::noskipws;

    // copy input to output, converting non-ASCII to hex:
    std::transform(std::istream_iterator<char>(infile),
        std::istream_iterator<char>(),
        std::ostream_iterator<std::string>(std::cout),
        [](char ch) {
            return (ch >= ' ') && (ch < 127) ?
                std::string(1, ch) :
                to_hex(ch);
    });
}

Twifty · Accepted Answer · 2013-07-15 09:39:51Z

Sounds to me like a utf8 issue. Since you didn't tag your question with c++11 Here Is an excelent article on unicode and c++ streams.

From your updated code, let me explain what is happening. You create a file stream to read your file. Internally the file stream only recognizes chars, until you tell it otherwise. A char, on most machines, can only hold 8 bits of data, but the characters in your file are using more than 8 bits. To be able to read your file correctly, you NEED to know how it is encoded. The most common encoding is UTF-8, which uses between 1 and 4 chars for each character.

Once you know your encoding, you can either use wifstream (for UTF-16) or imbue() a locale for other encodings.

Update: If your file is ISO-88591 (from your comment above), try this.

wifstream myReadFile;
myReadFile.imbue(std::locale("en_US.iso88591"));
myReadFile.open("11.txt");

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