[SmG FlasH™]

first off, dont return 0 from your randomgen function, and dont use global variables to store your random number. just return the randomcid from the randomgen function. then in your for loop, you are going to have to have an embedded for loop to check to see if the randomcid appears anywhere in the array. if it does you will have to generate a new one, otherwise you can use it. also when declaring your array, make all indexes that you dont want to use 0, that way you can tell if it has been assigned or not, as your randomgen will not produce a 0.

Oh okay. I forgot to mention, I'm not creating all the IDs' at once. There is a function named Register Customer in which the customer is prompted to enter his details (name, address, etc) So when a new customer registers, it has to create a unique ID for that customer. (Only 1). So basically when a new customer registers it has to do this generating thing.