The problem with fprintf

I write some codes below
FILE * fp;
int j=0;
char FileName[100]={0};

sprintf(FileName,"C:\\mttemp.txt");

if((fp=fopen(FileName,"a+"))!=NULL)
{

j=fprintf(fp,"hello\n");
fclose(fp);
}

After execute it , var j is 6,and the new file C:\mttemp.txt was created,but there is nothing in the file C:\mttemp.txt.
What's wrong?

Hi.

Your code works fine on my system. When do you view the file? You have to wait until the call to fclose( fp ) is finished. Since you used buffered I/O the text is first written to some buffer and not directly to the file. Check the contents of your file AFTER fclose(fp).

Peter

...or call fflush after fprintf.

Thanks very much, Peter and marsh. i have resolved the problem.