fseek vs fseeko64; whats the difference?

**johny145** · 08-03-2005

I have a problem using fseeko64
this is what i have tried

Code:

            fseek(ci.saveHandles[0],0,SEEK_END);
            fgetpos(ci.saveHandles[0],&curPos); // works, curPos = end of file

Code:

            fseeko64(ci.saveHandles[0],0,SEEK_END);
            fgetpos(ci.saveHandles[0],&curPos); // does not work , curPos = 0

Code:

            fseeko64(ci.saveHandles[0],0,SEEK_END);
            fseeko64(ci.saveHandles[0],0,SEEK_END);
            fgetpos(ci.saveHandles[0],&curPos); //works, curPos = end of file

Code:

            clearerr(ci.saveHandles[0]);
            fseeko64(ci.saveHandles[0],0,SEEK_END);
            fgetpos(ci.saveHandles[0],&curPos); //does not work

so something is wrong with the stream, but i dont know what. ferror returns 0 which means that there shouldnt not be anything wrong with it. Why isnt it possible to seplace all fseek's with fseeko64??

and since im still new to the usage of 64 bit file operations, is there anything else i should now about their usage?

(im still on winxp with mingw)

**johny145** · 08-04-2005

I found the solution. When a file is oped in "wb" mode the file has to be flushed before using fseeko64. fseek doesnt need a flush to work correctly

Code:

	FILE* myFile;
	long long pos = 0;
	myFile= fopen64("somefile.txt","wb");
	fprintf(myFile,"************************");
	//fflush(myFile); // if enabled it does work
	fseeko64(myFile,0,SEEK_END);
	pos = ftello64(myFile);

Is this behaviour intentionaly? Now i have to flush after writing or before using fseeko64

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