👀 Views: 19 💬 Answers: 1 📅 Created: 2025-06-13

c strings strncpy buffer-overflow null-termination C

I'm confused about I've been banging my head against this for hours. I'm dealing with I tried several approaches but none seem to work. I'm relatively new to this, so bear with me... I'm working with an scenario while trying to pad a string to a specific length using `strncpy` in C. My goal is to ensure that a string is always 10 characters long, padding it with spaces if it's shorter. However, I noticed that the output is not as expected when the input string has a length greater than 10 characters. Here's the code I'm using: ```c #include <stdio.h> #include <string.h> void padString(char *output, const char *input, size_t length) { strncpy(output, input, length); output[length - 1] = '\0'; // Ensure null termination } int main() { char result[11]; // 10 chars + null terminator const char *inputString = "Hello, World!"; padString(result, inputString, sizeof(result)); printf("Padded String: '%s'\n", result); return 0; } ``` When I run this code, I get the output `Padded String: 'Hello, Wor'`, which is what I expected, but I also get a warning about non-null termination if the input string is longer than the specified length. The warning suggests that `strncpy` doesn't null terminate the string if the source is longer than the given size. I want to seem to find a way to reliably pad the string to exactly 10 characters, while also handling cases where the input string might exceed this length. I've tried using `memset` to initialize `output` before calling `strncpy`, but that didn't resolve the warning. Additionally, I'm unsure if there's a better function or a best practice for handling such string manipulations in C. What would be the correct way to approach this question while ensuring proper null termination and avoiding buffer overflows? I'm working on a application that needs to handle this. For context: I'm using C on macOS. For context: I'm using C on Ubuntu 22.04. What's the correct way to implement this? My development environment is Ubuntu 20.04. I'm working on a REST API that needs to handle this. Am I approaching this the right way? This is for a REST API running on Ubuntu 22.04. Any advice would be much appreciated.