subprocess.Popen.stdout - reading stdout in real-time (again)

Again, the same question.
The reason is - I still can't make it work after reading the following:

• Real-time intercepting of stdout from another process in Python
• Intercepting stdout of a subprocess while it is running
• How do I get 'real-time' information back from a subprocess.Popen in python (2.5)
• catching stdout in realtime from subprocess

My case is that I have a console app written in C, lets take for example this code in a loop:

tmp = 0.0;   
printf("\ninput>>"); 
scanf_s("%f",&tmp); 
printf ("\ninput was: %f",tmp); 

It continuously reads some input and writes some output.

My python code to interact with it is the following:

p=subprocess.Popen([path],stdout=subprocess.PIPE,stdin=subprocess.PIPE)
p.stdin.write('12345\n')
for line in p.stdout: 
    print(">>> " + str(line.rstrip())) 
    p.stdout.flush() 

So far whenever I read form p.stdout it always waits until the process is terminated and then outputs an empty string. I've tried lots of stuff - but still the same result.

I tried Python 2.6 and 3.1, but the version doesn't matter - I just need to make it work somewhere.