the number of line in text file Cfile C++

Question

i want to print the number of line printed in C++ by using Cfile. i want to write the number of line according to the date. for example in the same file it is written for two days ,

Nr   date   time     code     value
1 10/6/2019  09:10   220      55
2 10/6/2019  10:16    33       23
3 10/6/2019  10:50    55       11
1 11/6/2019  03:55    11       15
2 11/6/2019  08:22    18       20

everything is right except the line number

CString strDate, strYearShort, strTime;

strYearShort = (CString)Datum.year;
strYearShort = strYearShort.Right(2);
strDate = (CString)Datum.day + '.' + (CString)Datum.month + '.' + strYearShort;
strTime = (CString)Zeit.hour + ':' + (CString)Zeit.minute;

buf.Format(_T("%s\t%s\t%s\t%s\t%s\t%d\r\n\r\n"), strDate, strTime, (CString)number, (CString)cardnumber, value);

enter code hereif (CTime::GetCurrentTime().GetDay() != lastWriteDay) {
        for (i = 1, i < 100, i++) {
            int Nu = i,
        }
    }
    else if (CTime::GetCurrentTime().GetDay() = lastWriteDay) {
        Nu == 0;
            or (i = 1, i < 100, i++) {
            Nu = i,
        }
    }

Answer 1

Keep a variable of the last write date:

// Should be persistent for lifetime of app:
// eg: global, static, or class member
int lastWriteDay = 0;

When writing a new line, compare last write date to the current date. If the dates are different, reset the line number.

....
if (CTime::GetCurrentTime().GetDay() != lastWriteDay) {
    number = 1;
    lastWriteDay = CTime::GetCurrentTime().GetDay();
}
// Do write....
....

Then you can update the number when you create the string:

buf.Format(_T("%s\t%s\t%d\t%d\t%s\t%d\r\n\r\n"),
    strDate,
    strTime,
    number++,    // Increment for next time
    cardnumber,
    value);

Also, the example in your question does not have enough parameters. And it seems unnecessary to convert the integers to CString. Just use the %d format specifier.

TODO: You might want to add some code that runs on startup that opens the file, reads the last line and parses the line to get the last write day. Then initialize lastWriteDay to that. This is needed for when the app has quit and restarted on the same day for some reason.