string変数はnullで初期化する

string変数を””で初期化すると、メモリが解放されない為、値代入と、””による初期化を、数十万回繰り返すと、MemoryOverFlowが発生する。

“”で初期化し、MemoryOverFlowが発生したソース。


int iRowCnt = 0;
string strRowData1000 = "";
string strRowData = "";
string strTmp = "";

foreach (DataGridViewRow row in grid.Rows)
{
    strRowData = "";
    for (int iCol = i開始列; iCol < row.Cells.Count; iCol++)
    {
        strRowData += "\"" + row.Cells[iCol].FormattedValue.ToString() + "\"";

        if ((grid.Columns.Count - 1) > iCol)
        {
            strRowData += ",";
        }
    }

    strTmp = strRowData.Replace(",", "").Replace("\"", "");
    if (strTmp.Length == 0)
        continue;
    else
        strRowData1000 += strRowData;

    if (iRowCnt < 2000)
    {
        strRowData1000 += "\r\n";
        iRowCnt++;
    }
    else
    {
        File.AppendAllText(str保存先ファイルパス, strRowData1000 + "\r\n", Encoding.GetEncoding("Shift_JIS"));
        iRowCnt = 0;
        strRowData1000 = "";
    }
}

int iRowCnt = 0;

string strRowData1000 = "";

string strRowData = "";

string strTmp = "";

foreach (DataGridViewRow row in grid.Rows)

{

strRowData = "";

for (int iCol = i開始列; iCol < row.Cells.Count; iCol++)

{

strRowData += "\"" + row.Cells[iCol].FormattedValue.ToString() + "\"";

if ((grid.Columns.Count - 1) > iCol)

{

strRowData += ",";

}

strTmp = strRowData.Replace(",", "").Replace("\"", "");

if (strTmp.Length == 0)

continue;

else

strRowData1000 += strRowData;

if (iRowCnt < 2000)

{

strRowData1000 += "\r\n";

iRowCnt++;

}

else

{

File.AppendAllText(str保存先ファイルパス, strRowData1000 + "\r\n", Encoding.GetEncoding("Shift_JIS"));

iRowCnt = 0;

strRowData1000 = "";

}

nullで初期化し、MemoryOverFlowが発生しなかったソース。


int iRowCnt = 0;
string strRowData1000 = "";
string strRowData = "";
string strTmp = "";

foreach (DataGridViewRow row in grid.Rows)
{
    strRowData = "";
    for (int iCol = i開始列; iCol < row.Cells.Count; iCol++)
    {
        strRowData += "\"" + row.Cells[iCol].FormattedValue.ToString() + "\"";

        if ((grid.Columns.Count - 1) > iCol)
        {
            strRowData += ",";
        }
    }

    strTmp = strRowData.Replace(",", "").Replace("\"", "");
    if (strTmp.Length == 0)
        continue;
    else
        strRowData1000 += strRowData;

    if (iRowCnt < 2000)
    {
        strRowData1000 += "\r\n";
        iRowCnt++;
    }
    else
    {
        File.AppendAllText(str保存先ファイルパス, strRowData1000 + "\r\n", Encoding.GetEncoding("Shift_JIS"));
        iRowCnt = 0;
        strRowData1000 = null;
    }
}

int iRowCnt = 0;

string strRowData1000 = "";

string strRowData = "";

string strTmp = "";

foreach (DataGridViewRow row in grid.Rows)

{

strRowData = "";

for (int iCol = i開始列; iCol < row.Cells.Count; iCol++)

{

strRowData += "\"" + row.Cells[iCol].FormattedValue.ToString() + "\"";

if ((grid.Columns.Count - 1) > iCol)

{

strRowData += ",";

}

strTmp = strRowData.Replace(",", "").Replace("\"", "");

if (strTmp.Length == 0)

continue;

else

strRowData1000 += strRowData;

if (iRowCnt < 2000)

{

strRowData1000 += "\r\n";

iRowCnt++;

}

else

{

File.AppendAllText(str保存先ファイルパス, strRowData1000 + "\r\n", Encoding.GetEncoding("Shift_JIS"));

iRowCnt = 0;

strRowData1000 = null;

}