Q What is the main difference between a function declaration and a function definition?
A The main difference between a function declaration and a function definition is that the former does not reserve any memory space, nor does it specify what a function does. A function declaration only alludes to a function definition that is placed elsewhere. It also specifies what type of arguments and values are passed to and returned from the function. A function definition, on the other hand, reserves the memory space and specifies tasks the function can complete.
Q Why do we need function prototypes?
A By declaring a function with prototypes, you specify not only the data type returned by the function, but also the types and names of arguments passed to the function. With the help of a function prototype, the compiler can automatically perform type checking on the definition of the function, which saves you time to debug the program.
Q Can a function return a pointer?
A Yes. In fact, a function can return a single value that can be any data type except an array or a function. A pointer value—that is, the address—returned by a function can refer to a character array, or a memory location that stores another type of data. For instance, the C library function asctime() returns a character pointer that points to a character string converted from a date-time structure.
Q Can you use top-down programming and bottom-up programming together to solve a problem?
A Yes. In practice, you can find that it's actually a good idea to combine the top-down and bottom-up programming approaches to solve problems. Using the two types of structured programming can make your program easy to write and understand.
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