Teshan2000/Stationary-Shop-Management-System ? reverse-engineered prompt

Build me a simple console based stationary shop management system in C for a small shop owner.

I want it to let me manage stock items, add new products, update quantities and prices, record sales, and keep basic customer and supplier details. It should also generate a clear invoice for each sale with item names, quantities, totals, and any other useful summary. The whole thing should feel like a menu driven POS style app that runs in the terminal and guides the user through each step.

Please keep it straightforward and practical, with data stored in a simple way that works for a local shop setup. Make sure the program is easy to compile and run from the command line, and include any needed instructions or sample usage if helpful. If something is unclear, use sensible defaults and look up current C documentation online if you need to.