struct phoneinfo { char name[MAX_NAME_LENGTH + 1]; char number[MAX_NUMBER_LENGTH + 1]; };Pass this entire array around among functions. If you want to pass a name/number pair, pass the entire structure.
Suppose that your array of phoneinfo structures is called info. Then info[i] has type phoneinfo. It is one entry in the phone book. Use info[i].name to get the name of the i-th entry, and info[i].number to get the number of the i-th entry.
Turn in a printout of your modified program, after you have tested it.