How ro save the cstring into the file

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i want to write the cstring into the file but iam not able to write the all datat into the file

What I have tried:

CString data = "[ERROR]: 2018-03-21 06:51:02 GMT"

fwrite(data, sizeof(data), 1, stream);
    
        fprintf(stream, "\n");
        fflush(stream);
        fclose(stream);

im getting o/p in file as "[ E R R"
could you please correct me if i am doing anything wrong here

Posted 20-Mar-18 20:55pm

Member 13089825

Updated 20-Mar-18 21:59pm

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Richard MacCutchan 21-Mar-18 5:07am

The simple answer is not to use fwrite, as that is basic C runtime. Use proper MFC classes for everything.

2 solutions

Solution 1

sizeof returns the size of the object, not it's content!
What you need is CString::GetLength[^]

Posted 20-Mar-18 21:12pm

OriginalGriff

Comments

Member 13089825 21-Mar-18 3:19am

i have used like below but still i am not able write all the string into the file
fwrite(data, data.GetLength(), 1, stream);
could you please correct me

OriginalGriff 21-Mar-18 4:07am

See Jochen's complete solution 2!

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Jochen Arndt · Accepted Answer · 2018-03-20T22:00:00

Besides using the correct length what is written to file depends also if your project is Unicode or not.

The correct solution to write the CString content "as it is" is:

fwrite(data.GetString(), sizeof(TCHAR), data.GetLength(), stream);

With Unicode builds, the CString content is stored internally as wchar_t which has a size of two bytes. With non-Unicode builds, it is stored as char. The TCHAR type is the corresponding character type according to the Unicode setting. Because CString::GetLength() returns the number of characters, the size has to be multiplied with the size of a character.

If you have a Unicode build but want to write to an ANSI file, you have to convert the string first to ANSI or use an ANSI string:

// Using ANSI string
CStringA dataA = "[ERROR]: 2018-03-21 06:51:02 GMT";
fwrite(dataA.GetString(), 1, dataA.GetLength(), stream);

// Writing ANSI with any build option
CString dataAny = _T("[ERROR]: 2018-03-21 06:51:02 GMT");
// This converts to ANSI with Unicode builds and copies otherwise
CStringA dataA(dataAny);
fwrite(dataA.GetString(), 1, dataA.GetLength(), stream);

Note the usage of CStringA which is the char version.