Week 7: Function Calls in C, Variables (Scope) in C, Program Organization, and Header Files

Question 1

The “STACK” is what?

Answer 1

The stack is the memory set aside as scratch space for a thread of execution. Reserved for each function call

Question 2

When calling a function, each parameter must…

Answer 2

Reduce down to a single value

Question 3

What is the difference between pass-by-reference and pass-by-value?

Answer 3

pass-by-reference means passing a variable by its location in memory, which allows a variable to be changed by a function

pass-by-value means literally passing he value stored in the variable with no way of changing the variable stored in main memory

Question 4

When accessing an array, using the name of the array is essentially….

Answer 4

Using the location in memory of the first item in the array

Question 5

dbray

and

&(dbray[0])

both mean…

Answer 5

The address of the first element of the array

Question 6

Arrays are actually…

Answer 6

Pointers

Question 7

double *ptr = &(array[0]);

is the same as….

Answer 7

double *ptr = array;

Question 8

The main difference between malloc and calloc is…

Answer 8

Malloc sets aside a certain number of bytes:
double *a;
a = ( double *) malloc (40);

Calloc sets aside a certain number of that type
double *a;
a = (double *) calloc ( 70, sizeof(double) );

Question 9

Static memory is ____ at the end of each use.

Dynamic memory is ______ at the end of each use unless ____

Answer 9

Static memory is deallocated at the end of each use.

Dynamic memory is not deallocated at the end of each use unless freed

Question 10

How do you free the following dynamic memory?

double *a;
a = ( double *) malloc (40);

Answer 10

free(a)

Question 11

Two ways of causing a memory leak are….

Answer 11

Not freeing the memory with free()

Reassigning the pointer variable to another place in dynamic memory before freeing it with free()

Question 12

What lines of code are required to set aside 70 double variables? Using malloc? Calloc? Calloc another way?

Answer 12

double *a;

a = (double)malloc(708);

or

a = (double)malloc(70(sizeof(double)));

or

a = (double*)calloc(70, 8);

or

a = (double *)calloc ( 70, sizeof(double) );

Question 13

What does a function prototype do?

Answer 13

Tell the preprocessor what to expect as a return type

Question 14

What is the format of a function protoytype?

Answer 14

float division(int , int , int* , int*);

Question 15

Function prototypes MUST

Answer 15

End with a semicolon

Question 16

To avoid including header files more than once…

Answer 16

endif // PROG1_H_INCLUDE

use the following format:

#ifndef PROG1_H_INCLUDED
     #define PROG1_H_INCLUDED

 #define NUMB int

 float rT;

 float division(int , int , int* , int*);

Question 17

What are the two categories of variable types in C?

Answer 17

Compile-time (allocated) variables
(The life time of these kinds of variables is the whole execution period of the C program)

Run-time variables
(The memory space used for these kinds of variables are allocated (reserved) during the
execution (running) of the program)

Question 18

What are the compile-time (allocated) variables in C?

Answer 18

Global variables — accessible everywhere

Static global variables — accessible within the same C program file

Static local variables — accessible within the same C function

Question 19

What are the run-time variables in C?

Answer 19

Local variables — accessible only in the block they are declared in

Parameter variables — accessible within the called function

Question 20

What is a parameter variable?

Answer 20

A variable accessible within the called function

Question 21

What is a local variable?

Answer 21

A variable accessible only in the block they are declared in

Question 22

What is a global variable?

Answer 22

A variable accessible everywhere

Question 23

What is a static global variable?

Answer 23

A variable accessible within the same C program file

Question 24

What is a static local variable?

Answer 24

A variable accessible within the same C function