advanced patterns of `strncpy` Leading to Uninitialized Memory Access in C
I've been struggling with this for a few days now and could really use some help... I've looked through the documentation and I'm still confused about I'm working on a project and hit a roadblock..... I'm working with unexpected behavior when using `strncpy` to copy strings in C. My intention is to copy a source string into a destination buffer while ensuring that the destination string is null-terminated. However, in some cases, it appears that the destination string is not getting properly initialized, leading to uninitialized memory access when I try to print it. Here’s a simplified version of my code: ```c #include <stdio.h> #include <string.h> void copy_string(char *dest, const char *src, size_t size) { strncpy(dest, src, size); } int main() { char buffer[10]; const char *source = "Hello, World!"; copy_string(buffer, source, sizeof(buffer)); printf("Copied string: '%s'\n", buffer); return 0; } ``` The output I expect is just the first 9 characters of `source`, but instead, I'm sometimes seeing garbage values or even causing a segmentation fault, depending on the input string. I suspect this is due to `strncpy` not null-terminating the string when the source length exceeds the specified size. I have tried manually adding a null terminator after the `strncpy` call: ```c if (strlen(source) >= sizeof(buffer)) { buffer[sizeof(buffer) - 1] = '\0'; } else { buffer[strlen(source)] = '\0'; } ``` Yet, I still experience issues. Is there a better approach to safely copy strings in C without running into uninitialized memory problems? What best practices should I follow to avoid these kinds of issues? Is there a better approach?