Bugs in Hello World Programs Across Multiple Languages

Hello World is traditionally the simplest introductory program, but a recent test of 16 common programming languages uncovered bugs in the Hello World implementations of seven languages.

Example in C (ANSI‑style)

#include <stdio.h>
#include <stdlib.h>
int main(void) {
    puts("Hello World!");
    return EXIT_SUCCESS;
}

This version follows the C standard, uses (void) for main, returns EXIT_SUCCESS, and includes the proper header for puts. However, it still contains a subtle bug when the program’s output is directed to a full device.

The Linux special file /dev/full behaves like /dev/null but reports a write error when data is written to it, simulating a “no space left on device” condition. Running the C program with its output redirected to /dev/full yields a successful exit status (0), even though the write operation fails:

$ gcc hello.c -o hello
$ ./hello > /dev/full
$ echo $?
0

Using strace shows the write system call returns -1 ENOSPC, confirming the error, yet the program still reports success, exposing a bug in error handling.

Similar tests were performed for other languages. Python 2 writes to /dev/full and prints a confusing error message to stderr but still exits with status 0. Python 3 correctly reports the error and exits with a non‑zero status (120). The full test matrix is summarized below:

Test results

Languages with bugs: C, C++, Python 2, Ruby, Java, Node.js, Haskell.

Languages without bugs: Rust, Python 3, Perl, Perl 6, Bash, Awk, OCaml, Tcl, C#.

The findings demonstrate that even the most elementary programs can silently ignore I/O errors, which may lead to data loss or unnoticed failures in real‑world applications. Proper error checking is essential, especially when programs are used as sanity checks or as part of larger pipelines.