How to remove accents and tilde in a C++ std::string

Question

I have a problem with a string in C++ which has several words in Spanish. This means that I have a lot of words with accents and tildes. I want to replace them for their not

Answer 1

    /// <summary>
    /// 
    /// Replace any accent and foreign character by their ASCII equivalent.
    /// In other words, convert a string to an ASCII-complient string.
    /// 
    /// This also get rid of special hidden character, like EOF, NUL, TAB and other '\0', except \n\r
    /// 
    /// Tests with accents and foreign characters:
    /// Before: "äæǽaeöœoeüueÄAeÜUeÖOeÀÁÂÃÄÅǺĀĂĄǍΑΆẢẠẦẪẨẬẰẮẴẲẶАAàáâãåǻāăąǎªαάảạầấẫẩậằắẵẳặаaБBбbÇĆĈĊČCçćĉċčcДDдdÐĎĐΔDjðďđδdjÈÉÊËĒĔĖĘĚΕΈẼẺẸỀẾỄỂỆЕЭEèéêëēĕėęěέεẽẻẹềếễểệеэeФFфfĜĞĠĢΓГҐGĝğġģγгґgĤĦHĥħhÌÍÎÏĨĪĬǏĮİΗΉΊΙΪỈỊИЫIìíîïĩīĭǐįıηήίιϊỉịиыїiĴJĵjĶΚКKķκкkĹĻĽĿŁΛЛLĺļľŀłλлlМMмmÑŃŅŇΝНNñńņňʼnνнnÒÓÔÕŌŎǑŐƠØǾΟΌΩΏỎỌỒỐỖỔỘỜỚỠỞỢОOòóôõōŏǒőơøǿºοόωώỏọồốỗổộờớỡởợоoПPпpŔŖŘΡРRŕŗřρрrŚŜŞȘŠΣСSśŝşșšſσςсsȚŢŤŦτТTțţťŧтtÙÚÛŨŪŬŮŰŲƯǓǕǗǙǛŨỦỤỪỨỮỬỰУUùúûũūŭůűųưǔǖǘǚǜυύϋủụừứữửựуuÝŸŶΥΎΫỲỸỶỴЙYýÿŷỳỹỷỵйyВVвvŴWŵwŹŻŽΖЗZźżžζзzÆǼAEßssIJIJijijŒOEƒf'ξksπpβvμmψpsЁYoёyoЄYeєyeЇYiЖZhжzhХKhхkhЦTsцtsЧChчchШShшshЩShchщshchЪъЬьЮYuюyuЯYaяya"
    /// After:  "aaeooeuueAAeUUeOOeAAAAAAAAAAAAAAAAAAAAAAAaaaaaaaaaaaaaaaaaaaaaaaBbCCCCCCccccccDdDDjddjEEEEEEEEEEEEEEEEEEeeeeeeeeeeeeeeeeeeFfGGGGGgggggHHhhIIIIIIIIIIIIIiiiiiiiiiiiiJJjjKKkkLLLLllllMmNNNNNnnnnnOOOOOOOOOOOOOOOOOOOOOOooooooooooooooooooooooPpRRRRrrrrSSSSSSssssssTTTTttttUUUUUUUUUUUUUUUUUUUUUUUUuuuuuuuuuuuuuuuuuuuuuuuYYYYYYYYyyyyyyyyVvWWwwZZZZzzzzAEssIJijOEf'kspvmpsYoyoYeyeYiZhzhKhkhTstsChchShshShchshchYuyuYaya"
    /// 
    /// Tests with invalid 'special hidden characters':
    /// Before: "\0\0\000\0000Bj��rk�\'\"\\\0\a\b\f\n\r\t\v\u0020���oacu\'\\\'te�"
    /// After:  "00000Bjrk'\"\\\n\r oacu'\\'te"
    /// 
    /// </summary>
    private string Normalize(string StringToClean)
    {
        string normalizedString = StringToClean.Normalize(NormalizationForm.FormD);
        StringBuilder Buffer = new StringBuilder(StringToClean.Length);

        for (int i = 0; i < normalizedString.Length; i++)
        {
            if (CharUnicodeInfo.GetUnicodeCategory(normalizedString[i]) != UnicodeCategory.NonSpacingMark)
            {
                Buffer.Append(normalizedString[i]);
            }
        }

        string PreAsciiCompliant = Buffer.ToString().Normalize(NormalizationForm.FormC);
        StringBuilder AsciiComplient = new StringBuilder(PreAsciiCompliant.Length);

        foreach (char character in PreAsciiCompliant)
        {
            //Reject all special characters except \n\r (Carriage-Return and Line-Feed). 
            //Get rid of special hidden character, like EOF, NUL, TAB and other '\0'
            if (((int)character >= 32 && (int)character < 127) || ((int)character == 10 || (int)character == 13)) 
            {
                AsciiComplient.Append(character);
            }
        }
        return AsciiComplient.ToString().Trim(); // Remove spaces at start and end of string if any
    }

Answer 2

I disagree with the currently "approved" answer. The question makes perfect sense when you are indexing text. Like case-insensitive search, accent-insensitive search is a good idea. "naïve" matches "Naïve" matches "naive" matches "NAİVE" (you do know that an uppercase i is İ in Turkish? That's why you ignore accents)

Now, the best algorithm is hinted at the approved answer: Use NKD (decomposition) to decompose accented letters into the base letter and a seperate accent, and then remove all accents.

There is little point in the re-composition afterwards, though. You removed most sequences which would change, and the others are for all intents and purposes identical anyway. WHat's the difference between æ in NKC and æ in NKD?

Answer 3

I could not link the ICU libraries but I still think it's the best solution. As I need this program to be functional as soon as possible I made a little program (that I have to improve) and I'm going to use that. Thank you all for for suggestions and answers.

Here's the code I'm gonna use:

for (it= dictionary.begin(); it != dictionary.end(); it++)
{
    strMine=(it->first);
    found=toReplace.find(strMine);
    while (found != std::string::npos)
    {
        strAux=(it->second);
        toReplace.erase(found,2);
        toReplace.insert(found,strAux);
        found=toReplace.find(strMine,found+1);
    }
} 

I will change it next time I have to turn my program in for correction (in about 6 weeks).

Answer 4

You might want to check out the boost (http://www.boost.org/) library.

It has a regexp library, which you could use. In addition it has a specific library that has some functions for string manipulation (link) including replace.

Answer 5

Try using std::wstring instead of std::string. UTF-16 should work (as opposed to ASCII).

Answer 6

If you can (if you're running Unix), I suggest using the tr facility for this: it's custom-built for this purpose. Remember, no code == no buggy code. :-)

Edit: Sorry, you're right, tr doesn't seem to work. How about sed? It's a pretty stupid script I've written, but it works for me.

#!/bin/sed -f
s/á/a/g;
s/é/e/g;
s/í/i/g;
s/ó/o/g;
s/ú/u/g;
s/ñ/n/g;