Unexpected behavior when using `strtok` with overlapping strings in C
I'm maintaining legacy code that I'm having a hard time understanding Quick question that's been bugging me - After trying multiple solutions online, I still can't figure this out... I'm encountering unexpected behavior when using `strtok` on overlapping strings in C. I have a string that I need to tokenize, and I'm passing the same string pointer to `strtok` multiple times. However, I noticed that when I attempt to tokenize a section of the string, the subsequent calls yield unexpected tokens. Here’s an excerpt of my code: ```c #include <stdio.h> #include <string.h> int main() { char str[] = "apple,banana,apple,orange"; char *token; // Tokenizing the first time token = strtok(str, ","); while (token != NULL) { printf("Token: %s\n", token); token = strtok(NULL, ","); } // Now trying to tokenize again on the same string token = strtok(str, ","); while (token != NULL) { printf("Token: %s\n", token); token = strtok(NULL, ","); } return 0; } ``` When I run this code, the output for the first tokenization is as expected: ``` Token: apple Token: banana Token: apple Token: orange ``` However, on the second attempt to tokenize, I get this output: ``` Token: apple Token: banana Token: apple Token: orange ``` I was expecting the second tokenization to start afresh, but it seems to be retaining the state from the first tokenization. I tried using `strdup` to create a copy of the string before tokenizing it again, but I still get the same result. Any insights into why this is happening? Is there a way to reset the state of `strtok` between tokenizations, or should I be using another function for this use case? I'm compiling with GCC version 10.2.0 on Ubuntu 20.04. Any help would be greatly appreciated! I'm working on a web app that needs to handle this. Any help would be greatly appreciated! For context: I'm using C on Ubuntu. What's the best practice here? Any suggestions would be helpful. Thanks for any help you can provide!