Your code exits the do loop after reading the first line. It will read the first line and discard the rest because you are closing the file. The fopen function is buffered I/O and will read all the lines in and discard them when fclose is called.Code:
std::stringstream msgsst; // stringstream to accumulate the input message char bufl; // last character in current fgets read buffer do{ // loop til you get a \n char msgbuf[msglen]; // fgets read buffer int len; // number of characters read fd = fopen(fifoname, "r"); // open the fifo fgets(msgbuf, msglen, fd); //read til \n, buffer full or EOF fclose(fd); // close the fifo len = strlen(msgbuf); // find number of characters read bufl = msgbuf[len-1]; // find the last character msgsst << msgbuf; // build up to complete input stringstream } while (bufl != '\n'); // keep going til you have a \n
I tried the following pair of programs on my Pi 5, running Bookworm.
C code "server" side program.
Code:
#include <stdio.h>int main(){ FILE *fp = fopen("/tmp/my_named_pipe", "w"); if (fp) { fprintf(fp, "one\ntwo\nthree\nfour\nfive\nsix\nseven\neight\nnine\nten\n"); } fclose(fp); return 0;}Code:
#include <cstdio>#include <cstring>#include <iostream>int main(){ FILE *fp = fopen("/tmp/my_named_pipe", "r"); if (fp) { char msgbuf[1024]; while (fgets(msgbuf, sizeof(msgbuf), fp)) { printf("Received %s", msgbuf); } fclose(fp); } return 0;}Code:
Received oneReceived twoReceived threeReceived fourReceived fiveReceived sixReceived sevenReceived eightReceived nineReceived tenStatistics: Posted by AndyD — Sun Feb 11, 2024 11:01 am