Functions, Pointers, & Arrays

Question 1

Function

Answer 1

When called, memory is allocated to the stack for its value parameters, local variables, and name (if not void). It calls statements until a return statement or at closing brace, then returns control to where it was called.

Question 2

What must happen before a function is called?

Answer 2

The compiler must process either the function protype or the function definition.

Question 3

Function Declaration

Answer 3

Identifier that names a function and specifies the number of parameters, type of each parameter, and type of return value.

Question 4

What is the basic syntax for a function declaration?

Answer 4

Return_type function_name(parameter declarations);
(also called the function prototype).

Question 5

What is the basic syntax for a function defenition?

Answer 5

Return_type function_name(parameter declarations) {
statements
}

Question 6

Formal Parameter

Answer 6

Dummy variable listed in the
subprogram header and used in the subprogram.

Question 7

Actual Parameter

Answer 7

Represents a value or address used in the subprogram call statement.

Question 8

Pass-By-Value

Answer 8

Pass a copy of the parameter value.

Question 9

Pass-By-Reference

Answer 9

Pass a reference to the parameter value (using a pointer or address).

Question 10

Default Parameters

Answer 10

Simple types, structs, and classes are value parameters by default but can be made reference parameters by using ‘&’ after their type. Arrays are always reference parameters.

Question 11

Reference Parameters

Answer 11

Used when the function is to assign or change the value of a variable from the calling block.

Question 12

Function Overloading

Answer 12

Functions with the same name but different number/type of parameters.

Question 13

Array

Answer 13

A group of elements of the same type in contiguous memory locations.

Question 14

Array Indexing

Answer 14

Accessing member x[i] requires calculation from x[0], the first element in the array.

Question 15

Characteristics of C/C++ Arrays

Answer 15

Do not behave like first-class objects; they cannot be copied using ‘=’. They do not remember how many items it can store and do not check for index validity.

Question 16

Array Indexing in C/C++

Answer 16

Creating an array creates a pointer to the first element in the array. For example, int x[10] creates an integer array with 10 elements and assigns x a constant pointer type (int*) with value &x[0].

Question 17

C-Style String

Answer 17

An array of characters ending with the null character ‘\0’. Can convert from C++ string to C-style using c_str().

Question 18

Pointer

Answer 18

A variable that contains a memory address. They can be used to access memory stored in the heap. Pointers must be explicitly declared and they must be initialized.

Question 19

Null Pointer

Answer 19

A special pointer value that does not refer to any valid memory location. It is given the ‘nullptr’ keyword.

Question 20

Pointer Assignment

Answer 20

One of two fundamental pointer operations. Used to set a pointer variable’s value to some useful
address. The ‘*’ operator is used for struct/class names while the ‘->’ operator is used for struct/class variables.

Question 21

Pointer Dereferencing

Answer 21

One of two fundamental pointer operations. Yields the value stored at the location represented by
the pointer’s value. Can be explicit or implicit.

Question 22

Dereferencing an Uninitialized/Null Pointer

Answer 22

Causes undefined behavior. There could be a crash, a core dump, or a segmentation fault.

Question 23

C/C++ Valid Pointer Operators

Answer 23

The operators ‘=’, ‘*’, and ‘->’ for pointers and the relational operators ‘==’ and ‘!=’.

Question 24

C/C++ Pointer Arithmetic

Answer 24

Pointers can be added to or subtracted from. Take the lines:
float stuff[100]
float *p;
p = stuff;
for example. *(p + 5) would point to stuff[5].

Question 25

References

Answer 25

Similar to a constant pointer; it contains a memory address and cannot be changed. It needs to be initialized when declared (compile error) and it cannot be dereferenced.

Question 26

Intermixing Pointers and Const

Answer 26

There are two ways pointers and constants can be mixed: 1. Constant pointer that cannot point to a different memory address, but the value it points to can be changed. Must be initialized upon declaration. 2. Pointer to a const variable, where the value of variable cannot be changed through the pointer but can be changed independently.

Question 27

Passing Arrays as Arguments

Answer 27

When an array is passed as an argument, the memory address of the first element in the array is called to the function (as a const pointer in C/C++). Parameters declared as int *ap and int ap[] work the same.

Question 28

C/C++ Main Function

Answer 28

Can take either no arguments or two arguments: int main() int main(int argc, char *argv[]) where argc is the number of C-type strings and argv is an array of pointers to C-style strings. Whether or not command-line arguments are passed, the first array entry will be the name of the program.