REACH CECS 130 Final Test Review Spring 2013

1. REACH CECS 130 Final Test Review Spring 2013

2. How to create arrays • data_typearray_name [number-of-elements]; • Two Dimensional Array array_typearray_name [number_of_ROWS][number_of_COLUMNS];

3. How to create pointers • type* pointer_name; • ex. int my_int; int* my_int_pointer = &my_int; Assigns the address of my_int to the pointer

4. Useful string functions • Copying strings from one to another • char* strcpy(char* p, const char* q); • char s[6]; strcpy(s, “Hello”); • To combine strings • char* strcat(char* p, const char* q); • char s[12] = “Hello” strcat(s, “World”);

5. Useful string functions • To copy n characters from q to the of p. • char* strncpy(char* p, const char* q, int n); • char s [7] = “Say “; char t[] = “Hi”; strncpy (s, t, 2)

6. String functions

7. Challenge question • Can you write a program using C++ that uses a FOR loop to initialize a 2D array that looks like the following {0,5,10,15}{0,2,4,6}

8. Answer #include<iostream> using namespace std; int main(){ int array[2][4], , row, column; for(row=0;row<2;row++) for(column=0;column<4;column++){ if(row==0) array[row][column]=column*5; else if(row==1) array[row][column]=column*2; } for(row=0; row<2; row++){ for(column =0; column <4; column ++) cout<<array[row][column]<<" "; cout<<endl; } system("pause"); return 0; }

9. Classes • Classes are general models from which you can create objects • Classes have data members either data types or methods • Classes should contain a constructor method and a destructor method • See handout for example of a program that utilizes a class

10. Declaring Classes class ClassName { memberList }; memberList can be either data member declarations or method declarations

11. Class Declaration Example Class Bow { //data member declarations string color; bool drawn; intnumOfArrows; Bow(string aColor); //constructor ~Bow(); //destructor //methods void draw(); int fire(); };

12. Creating Methods Return_type ClassName::methodName(argumentList) { methodImplementation }

13. Methods Creation Example //draws the bow void Bow::draw() { drawn = true; cout<< “The “<<color<<“bow has been drawn.”<<endl; }

14. Simple Data Structures

17. Passing Structures to Functions

18. Sizeof()

19. Malloc() Please enter how long your name is: 21 Please enter your name: Nawaf Hello Nawaf Please enter how long your name is: -7 Failed allocation memory

20. free()

21. Calloc and Realloc() int *n; int * n1; n=( int * ) calloc(5, sizeof(int)); // Reserves a block of memory for 5 integers //Decide you need to reallocate more memory later in the program n1= (int *) realloc(n, 10 * sizeof(int));//allocate 10 integers instead of 5 if (n1!=NULL) { n=n1; } else printf("Out of memory!"); realloc() returns null if unable to complete or a pointer to the newly reallocated memory.

22. How to declare and implement functions • Function declaration • Function definition • Function call

23. #include <iostream> using namespace std; int add(int, int); int main(void) { int number1, number2; cout << “Enter the first value to be summed:”; cin >> number1; cout << “\nEnter the second:”; cin >> number2; cout << “\n The sum is: “ << add (number1, number2) <<endl; } int add(int a, int b){return a+b;}

24. Functions Challenge • Write a function, called multiply that multiplies two numbers and returns the result

25. C - Files Do you know the syntax for each of these, used to read and write to data files? • Pointers: think of it as the memory address of the file • fopen() • fclose() • fscanf() • fprintf()

26. fopen(“file name”, “Mode”) • fopen() returns a FILE pointer back to the pRead variable • #include <cstdio> • Main() • { FILE *pRead; • pRead = fopen(“c:\\folder1\\folder2\\file1.dat”, “r”); • if(pRead == NULL) • printf(“\nFile cannot be opened\n”); • else • printf(“\nFile opened for reading\n”); • fclose(pRead); • }

27. What does this code do? int main () { FILE * pFile; char c; pFile=fopen("alphabet.txt","wt"); for (c = 'A' ; c <= 'Z' ; c++) { putc (c , pFile);//works like fprintf } fclose (pFile); return 0; }

28. Common Text File Modes

29. fclose(file pointer) • Pretty basic. • Always close files when you use fopen.

30. fscanf(FILE pointer, “data type”, variable in which to store the value) • Reads a single field from a data file • “%s” will read a series of characters until a white space is found • can do fscanf(pRead, “%s%s”, name, hobby);

31. #include <stdio.h> • Main() • { • FILE *pRead; • char name[10]; • pRead = fopen(“names.dat”, “r”); • if( pRead == NULL ) • printf( “\nFile cannot be opened\n”); • else • printf(“\nContents of names.dat\n”); • fscanf( pRead, “%s”, name ); • while( !feof(pRead) ) { // While end of file not reached • printf( “%s\n”, name ); // output content of name • fscanf( pRead, “%s”, name ); // scan from file next string • } • fclose(pRead); • }

32. Quiz Kelly 11/12/86 6 Louisville Allen 04/05/77 49 Atlanta Chelsea 03/30/90 12 Charleston Can you write a program that prints out the contents of this information.dat file?

33. #include <stdio.h> • Main() • { • FILE *pRead; • char name[10]; • char birthdate[9]; • float number; • char hometown[20]; • pRead = fopen(“information.dat”, “r”); • if( pRead == NULL ) • printf( “\nFile cannot be opened\n”); • else • fscanf( pRead, “%s%s%f%s”, name, birthdate, &number, hometown ); • while( !feof(pRead) ) { • printf( “%s \t %s \t %f \t %s\n”, name, birthdate, number, hometown ); • fscanf( pRead, “%s%s%f%s”, name, birthdate, &number, hometown ); • } • fclose(pRead); • }

34. fprintf(FILE pointer, “list of data types”,list of values or variables) • The fprintf() function sends information (the arguments) according to the specified format to the file indicated by stream. fprintf() works just like printf() as far as the format goes.

35. #include <stdio.h> Main() { FILE *pWrite; char fName[20]; char lName [20]; float gpa; pWrite = fopen(“students.dat”,”w”); if( pWrite == NULL ) printf(“\nFile not opened\n”); else printf(“\nEnter first name, last name, and GPA ”); printf(“separated by spaces:”); scanf(“%s%s%f”, fName, lName, &gpa); fprintf(pWrite, “%s \t %s \t % .2f \n”, fName, lName, gpa); fclose(pWrite); }

36. Quiz • Can you write a program that asks the user for their • Name • Phone Number • Bank account balance And then prints this information to a data file called accounts.dat ?

37. exit() /* exit example */ #include <stdio.h> #include <stdlib.h> int main () { FILE * pFile; pFile = fopen ("myfile.txt","r"); if (pFile==NULL) { printf ("Error opening file"); exit (EXIT_FAILURE); } else { /* file operations here */ } return 0; }

38. perror() /* perror example */ #include <stdio.h> int main () { FILE * pFile; pFile=fopen ("unexist.ent","rb"); if (pFile==NULL) perror ("The following error occurred"); else fclose (pFile); return 0; }

39. Function overloading • void swap (int *a, int *b) ; • void swap (float *c, float *d) ; • void swap (char *p, char *q) ; • The other way is to have different number of input parameters for the function

40. Default Arguments int boxVolume(int length = 1, int width = 1,int height = 1) { return (length * width * height); } If the function was called with no parameters then the default values will be used.

41. Scope :: • Used to go out one level. • If you have a global and local variables with same name, and need to call global from local scope then you need to use ::VariableName

42. Static vs. Automatic variables • All your declared variables are automatic. • Static variables keep there values as long as they exist.

43. OOP • Declare classes • Create objects • 3 MAIN PRINCIPLES OF OOP • Data abstraction – hiding data members and implementation of a class behind an interface so that the user of the class corrupt that data • Encapsulation – each class represents a specific thing or concept. Multiple classes combine to produce the whole • Polymorphism-objects can be used in more than one program

44. Classes • Classes are general models from which you can create objects • Classes have data members either data types or methods • Classes should contain a constructor method and a destructor method • See handout for example of a program that utilizes a class

45. Declaring Classes class ClassName { memberList }; memberList can be either data member declarations or method declarations

46. Class Declaration Example Class Bow { //data member declarations string color; bool drawn; intnumOfArrows; Bow(string aColor); //constructor ~Bow(); //destructor //methods void draw(); int fire(); };

47. Creating Methods Return_type ClassName::methodName(argumentList) { methodImplementation }

48. Methods Creation Example //draws the bow Void Bow::draw() { drawn = true; cout<< “The “<<color<<“bow has been drawn.”<<endl; }

49. Union Output: 9 3.1416 #include <stdio.h> #include<stdlib.h> union NumericType { int iValue; long lValue; double dValue; }; int main() { union NumericType Values; // iValue = 10 Values.iValue=9; printf("%d\n", Values.iValue); Values.dValue = 3.1416; printf("%f\n", Values.dValue); system("pause"); }

50. Inline function • An inline function is one in which the function code replaces the function call directly. #include <stdio.h> inline void test(void){ puts("Hello!");} int main () { test(); // This will be replaced with puts("Hello!") on run time return 0; }