C/C++ :: How To Get CTRL Z To Close A Pipe

My 'c' program reads each line of a .txt file, makes a few changes and then outputs the line of text (which are names). I want the contents to be sorted and did not want to bother writing my own sort. The program runs in a command prompt from inside a batch file for example:

sort | makelist.exe BluRay1.txt > sorted.txt
sort | makelist.exe Dvd1.txt >> sorted.txt
..etc..

I have to supply a ctrl-z manually to close the piping. I tried the following which did not work.

buffer[0] = 26;

printf("%c",buffer[0]);
//printf("^(z)");
fclose(stdout);
fclose(stdin);

I never got the above to work so I am avoiding piping and just do a redirect instead.

makelist.exe dvd1.txt > unsorted.txt
makelist.exe dvd2.txt >> unsorted.txt
sort < unsorted.txt > sorted.txt

..etc.

Just wondering if I could have gotten the ctrl-z thru the pipe using "C".