this problem is not hard. i don't rember the detail about C right now, but i can give you some ideas!
1. write a function: menu -use printf
2. write a function to distribute the jobs.
in the function, you can use switch
switch(option)
{
case 1: newCustomer();
break;
case 2: search()
break;
case 3: displayAllCustomers()
break;
}
3. write each sub-functions
int newCustomers()
{
//use scanf to get the information from customers
// use if else to ask wether the user wants to save
if yes,
use fprintf or fputs to save into the file
else
return;
}
4.
int search()
{
// use fscanf or fgets to get data from source file and store them by using pointers
// you can search by name by using some algrithms. this depends on how you store the data
return 1 if you get it. otherwise, return 0;
}
5. void displayAllCustomers()
{
// this one is actually the first part of search
you should get data from file. then print them out( you can use fscanf and fprintf here)
}
i hope this can help you!! GOOD LUCK FOR YOUR TEST