How to split char pointer with multiple delimiters & return array of char pointers in c++?

Question

In the duplicate of this question Split char* to char * Array it is advised to use string rather than char*. But I need to work with LPWSTR. Since it's a typedef of char*, I prefer to use char*. I tried with the following code, which gives the wrong output:

char**splitByMultipleDelimiters(char*ori,char deli[],int lengthOfDelimiterArray)
{
    char*copy = ori;
    char** strArray = new char*[10];
    int j = 0;
    int offset = 0;
    char*word = (char*)malloc(50);
    int length;
    int split = 0;
    for(int i = 0; i < (int)strlen(ori); i++)
    {
        for(int k = 0; (k < lengthOfDelimiterArray) && (split == 0);k++)
        {
            if(ori[i] == deli[k])
            {
                split = 1;
            }
        }
        if(split == 1)//ori[i] == deli[0]
        {
            length = i - offset;
            strncpy(word,copy,length);
            word[length] = '\0';
            strArray[j] = word;
            copy = ori + i + 1;
            //cout << "copy: " << copy << endl;
            //cout << strArray[j] << endl;
            j++;
            offset = i + 1;
            split = 0;
        }
    }
    strArray[j] = copy;
   // string strArrayToReturn[j+1];
    for(int i = 0; i < j+1; i++)
    {
        //strArrayToReturn[i] = strArray[i];
        cout << strArray[i] << endl;
    }
    return strArray;
}

void main()
{
        char*ori = "This:is\nmy:tst?why I hate";
        char deli[] = {':','?',' ','\n'};

        int lengthOfDelimiterArray = (sizeof(deli)/sizeof(*deli));
        splitByMultipleDelimiters(ori,deli,lengthOfDelimiterArray);
}

Are there any other ways to split LPWSTR?

Use LPWSTR only where you need it. Why make it harder to process the string simply because you'd need a conversion to a C string later (which can usually be done with c_str)? — Qaz
– Qaz, Commented Aug 7, 2015 at 17:21
LPWSTR isn't a pointer to an array of char. it's a pointer to an array of wide char. You're going to have to shift your thinking to unicode, my friend. — user4581301
– user4581301, Commented Aug 7, 2015 at 17:38
"Wrong output" is not an error description. Since noone is going to read your mind, to understand what you expected to be the correct output, this isn't very helpful. When describing an error, always include both expected behavior and observed behavior. — IInspectable
– IInspectable, Commented Aug 8, 2015 at 14:26

Community · Accepted Answer · 2017-05-23 12:29:43Z

0

Wait, what are you talking about? I don't see LPWSTR anywhere in your code. Are you trying to convert to LPWSTR? If so, there's a standard library function for that. There's also a standard library-based solution for splitting over multiple chars. So all together, your code might look like this:

#include <codecvt>
#include <cstdio>
#include <locale>
#include <sstream>
#include <string>

using std::string;
using std::wstring;

wstring toWide(const string &original)
{
    std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
    return converter.from_bytes(narrow_utf8_source_string);
}

std::vector<wstring> splitMany(const string &original, const string &delimiters)
{
    std::stringstream stream(original);
    std::string line;

    while (std::getline(original, line)) 
    {
        std::size_t prev = 0, pos;
        while ((pos = line.find_first_of(delimeters, prev)) != std::string::npos)
        {
            if (pos > prev)
                wordVector.push_back(line.substr(prev, pos-prev));
            prev = pos + 1;
        }
        if (prev < line.length())
            wordVector.push_back(line.substr(prev, std::string::npos));
    }
}

int main()
{
    string original = "This:is\nmy:tst?why I hate";
    string separators = ":? \n"

    std::vector<wstring> results = splitMany(original, separators);
}

This code uses the standard library for these functions and is much less error-prone than doing it manually.

Good luck!

Edit: To be clear, wstring == LPWSTR == wchar_t*.

Edit 2: To convert a string to a wstring:

#include <codecvt>
#include <locale>
#include <string>

using std::string;
using std::wstring;

string toMultiByte(const wstring &original)
{
    std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
    return converter.to_bytes(original);
}

edited May 23, 2017 at 12:29

CommunityBot

11 silver badge

answered Aug 7, 2015 at 17:51

James Ko

34.9k34 gold badges148 silver badges258 bronze badges

Sign up to request clarification or add additional context in comments.

11 Comments

Janu Over a year ago

Thanks for your answer. Are there any standard function to split or parse LPWSTR other than converting and split?

James Ko Over a year ago

@Janu I don't understand; you're asking how to convert or split wstring without converting or splitting them? If you're asking how to do something like parse a number from a wstring, then yes there is a standard library utility to parse numbers from a wstring. Basically all the things you can do with string are available for wstring as well, check out the C++ reference for wstring.

Janu Over a year ago

I need to parse LPWSTR (eg: computer name: Janu\nuser name: Janaki) and retrieve Janu as computer name and Janaki as user name. To retrive like this, I need to split the LPWSTR.

James Ko Over a year ago

@Janu Then you'll have to convert from std::wstring to string. See my updated answer for instructions on how to do this.

Jonathan Potter Over a year ago

@JamesKo This is Windows, the source string is unlikely to be UTF8.

|

Collectives™ on Stack Overflow

How to split char pointer with multiple delimiters & return array of char pointers in c++?

1 Answer 1

11 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

11 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related