如何在两个进程之间发送带管道的整数！

Question

I am trying to send an integer with pipe in a POSIX system but write() function is working for sending string or character data. Is there any way to send integer with a pipe?

Regards

Answer 1

The safe way is to use snprintf and strtol .

But if you know both processes were created using the same version of compiler (for example, they're the same executable which fork ed), you can take advantage of the fact that anything in C can be read or written as an array of char :

int n = something();
write(pipe_w, &n, sizeof(n));

int n;
read(pipe_r, &n, sizeof(n));

Answer 2

Either send a string containing the ASCII representation of integer eg, 12345679 , or send four bytes containing the binary representation of int, eg, 0x00 , 0xbc , 0x61 , 0x4f .

In the first case, you will use a function such as atoi() to get the integer back.

Answer 3

Aschelpler的答案是正确的，但如果这可以在以后增长，我建议您使用某种简单的协议库，如Google的Protocol Buffers，或只使用JSON或XML和一些基本架构。

Answer 4

Below one works fine for writing to pipe and reading from pipe as:

stop_daemon =123;
res = write(cli_pipe_fd_wr, &stop_daemon, sizeof(stop_daemon));
....
res = read(pipe_fd_rd, buffer, sizeof(int));
memcpy(&stop_daemon,buffer,sizeof(int));
printf("CLI process read from res:%d status:%d\n", res, stop_daemon);

output:

CLI process read from res:4 status:123