Formatted output with MPI_File_write_at?

Question

I'm trying to write a parallel IO program with MPI, I'm required to write the data to the file with a format as: 02 03 04 in the file instead of 2 3 4.

fprintf(fpOut,"%.2d ",var);

Would be the serial counterpart of what I'm trying to do. I've looked around but couldn't find any answers so far. Any idea on how I might go about this?

score 1 · Accepted Answer · answered May 02 '20 at 03:34

MPI_IO writes binary data (vs text/formatted data).

So if you really want to write in parallel, you can use an intermediate buffer, and then write it, for example

char buf[4];
sprintf(buf, "%.2d ", var);
MPI_File_write_at(buf, 3, MPI_CHAR, ...);

That being said, you might want to reconsider your workflow:

one option is to start using binary data everywhere (and write in parallel)
an other option is to write intermediate data in binary and in parallel, and finally post process it (not in parallel) to "convert" it into plain text.

Formatted output with MPI_File_write_at?

1 Answers1