fclose & fopen VS freopen

[AhmedKamal]

freopen is supposed to close a file and open another right?
then why not use fclose followed by an fopen
I tried this appraoch with a normal file and it worked
but by using this with stdout it didn't work i had to use freopen
why is that?

The first one was

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
FILE * fp = fopen("example.txt", "w");
fprintf(fp, "this is the first time\n");
fclose(fp);
fp = fopen("example2.txt", "w");
fprintf(fp, "this is the second time\n");
fclose(fp);
return 0;
}

this is the second one with stdout that didn't work (didn't write anything to the example.txt)

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
fclose(stdout);
if (! (stdout = fopen("example.txt", "w"))) perror("Failed");;
printf("hey\n");
return 0;
}


BUT IN THE LAST EXAMPLE IF I CHANGE printf("hey\n"); to fprintf(stdout, "hey\n"); it works and printf is supposed to print to the stdout why does this happen?

[kooth]

What error did you see?

[ne555]

man pages wrote:

Since the symbols stdin, stdout, and stderr are specified to be macros, assigning to them is non-portable.
The standard streams can be made to refer to different files with help of the library function freopen(3), specially introduced to make it possible to reassign stdin, stdout, and stderr.

[AhmedKamal]

@kooth it doesn't give an error it just doesn't write anything in the file "example.txt"

@ne555 that makes me think of another question. What is that macro exactly? I tried to open the stdio.h file and didn't find an exact description of what it is? i'm just wondering

[kbw]

freopen is supposed to close a file and open another right?

Wrong. The effect of freopen is to reassign a handle to another source.

In your example (that works) fp is reassinged from writing to example.txt to example2.txt

[AhmedKamal]

I"M SORRY I had put another example for example one than the one I meant to post I have changed it and written another note in the end