How can I make a time down timer in c language?

Question

I want to make a time down timer in c language but I haven't idea for this program so please help me

Answer 1

https://www.codeproject.com/Tips/82005/A-count-down-timer-in-c

https://cboard.cprogramming.com/c-programming/112560-timers-c.html

https://stackoverflow.com/questions/17167949/how-to-use-timer-in-c

https://www.youtube.com/watch?v=4KglSME_9yk