advanced patterns when using `strncpy` for string concatenation in C - Need clarification on buffer handling
I'm working through a tutorial and I tried several approaches but none seem to work. I've tried everything I can think of but I'm trying to configure I'm working with an unexpected behavior when trying to concatenate two strings using `strncpy`. I initially assumed that `strncpy` would automatically null-terminate the destination string if the source string's length is less than the specified size. Here’s what I tried: ```c #include <stdio.h> #include <string.h> int main() { char dest[10] = "Hello"; char src[] = "World"; strncpy(dest + 5, src, sizeof(src)); // Expected output: HelloWorld printf("%s\n", dest); return 0; } ``` However, when I run this code, I get the output `HelloWorld` as expected, but when I change `sizeof(src)` to `3`, I encounter a question. Instead of seeing `HelloWor`, I get `HelloWor\u0000` in my debug output, indicating that it doesn't null-terminate as I expected. I was under the impression that `strncpy` would fill the remaining space with null characters, but it seems that is not the case when the source string is shorter than the specified length. Additionally, I tried checking the behavior in different compilers (GCC version 10.2 and Clang version 12.0) and noticed the same result. Can someone clarify how `strncpy` works in this context? What is the best way to safely concatenate strings while ensuring null-termination? Should I consider using `snprintf` for this task instead? Any advice would be appreciated! Any ideas what could be causing this? I recently upgraded to C LTS. Thanks in advance! I appreciate any insights! I'm working on a CLI tool that needs to handle this.