How to write data to SD card in MPS3

I downloaded the example "Example CoreLink SSE-200 Subsystem_for_MPS3".

There seems to be no mention in the example how to write data to the SD card.

But I found that the example supports "stdio.h".

So I tried to specify the path with "fopen" but it didn't work. ("fopen" return a null pointer)

How can I write the data into the sd card?

FILE *fp;	
fp = fopen("F:\\test.txt", "w");
if(fp==NULL)
{
	printf("Output Error!\n");
}
else
{
	fprintf(fp, "Hello\n" );
}

Contents of stdio.h:

stdio.h

Result of execution:

Result of execution