Function CSLRemoveStrings

port/cpl_string.cpp:572–635

 */

char **CSLRemoveStrings(char **papszStrList, int nFirstLineToDelete,
                        int nNumToRemove, char ***ppapszRetStrings)
{
    const int nSrcLines = CSLCount(papszStrList);

    if (nNumToRemove < 1 || nSrcLines == 0)
        return papszStrList;  // Nothing to do!

    // If operation will result in an empty StringList, don't waste
    // time here.
    const int nDstLines = nSrcLines - nNumToRemove;
    if (nDstLines < 1)
    {
        CSLDestroy(papszStrList);
        return nullptr;
    }

    // Remove lines from the source StringList.
    // Either free() each line or store them to a new StringList depending on
    // the caller's choice.
    char **ppszDst = papszStrList + nFirstLineToDelete;

    if (ppapszRetStrings == nullptr)
    {
        // free() all the strings that will be removed.
        for (int i = 0; i < nNumToRemove; ++i)
        {
            CPLFree(*ppszDst);
            *ppszDst = nullptr;
        }
    }
    else
    {
        // Store the strings to remove in a new StringList.
        *ppapszRetStrings =
            static_cast<char **>(CPLCalloc(nNumToRemove + 1, sizeof(char *)));

        for (int i = 0; i < nNumToRemove; ++i)
        {
            (*ppapszRetStrings)[i] = *ppszDst;
            *ppszDst = nullptr;
            ++ppszDst;
        }
    }

    // Shift down all the lines that follow the lines to remove.
    if (nFirstLineToDelete == -1 || nFirstLineToDelete > nSrcLines)
        nFirstLineToDelete = nDstLines;

    char **ppszSrc = papszStrList + nFirstLineToDelete + nNumToRemove;
    ppszDst = papszStrList + nFirstLineToDelete;

    for (; *ppszSrc != nullptr; ++ppszSrc, ++ppszDst)
    {
        *ppszDst = *ppszSrc;
    }
    // Move the NULL pointer at the end of the StringList.
    *ppszDst = *ppszSrc;