Every snippet in this post passes on a developer machine set to US English. Then someone in Istanbul, Berlin or London runs it, or data arrives from another system, and it quietly does the wrong thing. To reproduce that, the demo sets the culture per "user" before each run.
Source: [Dev.to](https://dev.to/nazecode/5-c-string-bugs-that-only-happen-on-someone-elses-machine-da2)