在 C 中从管道写入和读取整数

Question

I am trying to understand using pipes in C, specifically writing and reading integers. I have a parent process that creates 3 child processes. Two of the child processes calculate numbers and write them to a pipe. The third process reads from both pipes and then displays. Sounds simple right?

I found this post: How to send integer with pipe between two processes! on how to send integers through pipes and followed it, but I am not producing the correct output.

Edit: for further clarification, I initiate the pipes like so:

int p1[2]; //pipe1 
int p2[2]; //pipe2
pipe(p1); //intialize pipe1 for between process 1 & 3
pipe(p2); //initialize pipe2 for between process 2 & 3

After some debugging, I notice that the wrong number is being written to the pipe. This is how I am writing an int to the pipe:

int c0 = 18;
write(p2[1], &c0, sizeof(c0));

and this is how I am reading:

int disp[4];
read(p1[0], &disp[0], sizeof(disp[0]));

and so on until the array is full.

Now instead of writing something like 14 to the pipe, it writes a large number like 17462. I am assuming that it is writing the address, right? If so, how would I write the actual integer to the pipe? Should I remove the '&' from the statements, because doing that gives me errors about casting. Any tips, advice, comments are always appreciated. Thanks.

Answer 1

You probably need to get write locks on the pipe.

If process 1 and process 2 writes to the pipe simultaneously, you might get bytes mixed in the pipe such that the resulting read will be some strange number you've never seen.