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EECE.2160 ECE Application Programming

EECE.2160 ECE Application Programming. Instructor: Dr. Michael Geiger Fall 2017 Lecture 27: Nested structures. Lecture outline. Announcements/reminders Program 6 graded; regrades due 11/29 Program 7 posted; due 11/20 Programs submitted 11/21-11/26 “ 1 day late ”

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EECE.2160 ECE Application Programming

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  1. EECE.2160ECE Application Programming Instructor: Dr. Michael Geiger Fall 2017 Lecture 27: Nested structures

  2. Lecture outline • Announcements/reminders • Program 6 graded; regrades due 11/29 • Program 7 posted; due 11/20 • Programs submitted 11/21-11/26 “1 day late” • Late penalties begin increasing again on 11/27 • Today’s class • Structures and functions example • Nested structures • Start PE4 (Structures) ECE Application Programming: Lecture 27

  3. Review: Structures • User-defined types; example: typedef struct { char first[50]; char middle; char last[50]; unsigned int ID; double GPA; } StudentInfo; • Can define variables of that type • Scalar: StudentInfo student1; • Array: StudentInfo classList[10]; • Pointer: StudentInfo *sPtr = &student1; • Access members using • Dot operator: student1.middle = ‘J’; • Arrow (if pointers): sPtr->GPA = 3.5; • Typically passed to functions by address ECE Application Programming: Lecture 27

  4. Review: Structures and functions • Can pass structures to functions • int f(StudentInfo s); • Structures consume significant memory • Usually much more efficient to simply pass pointer • int g(StudentInfo *p); • Access structure through pointer: -> operator • Handles dereferencing and field access • Example: p->GPA = 3.0; ECE Application Programming: Lecture 27

  5. Example: Structures and functions • Write the following functions that use the StudentInfo structure • Given a pointer to a single StudentInfo variable, print all of the student info to the screen using the following format: Michael J. Geiger ID #12345678 GPA: 1.23 • Given an array of StudentInfo variables and the size of the array, compute and return the average GPA of all students in the list • Prompt the user to enter 3 lines of input (using the format below), read the appropriate values into StudentInfo elements, and return a value of type StudentInfo • Format (user input underlined) Enter name: Michael J. Geiger Enter ID #: 12345678 Enter GPA: 1.23 ECE Application Programming: Lecture 27

  6. Example solution void printStudent(StudentInfo *s) { printf(“%s %c. %s\n”, s->first, s->middle, s->last); printf(“ID #%u\n”, s->ID); printf(“GPA %.2lf\n”, s->GPA); } ECE Application Programming: Lecture 27

  7. Example solution (cont.) double avgGPA(StudentInfo list[], int n) { int i; int sum = 0; for (i = 0; i < n; i++) sum += list[i].GPA; return sum / n; } ECE Application Programming: Lecture 27

  8. Example solution (cont.) StudentInfo readStudent() { StudentInfo s; printf(“Enter name: ”); scanf(“%s %c. %s”, s.first, &s.middle, s.last); printf(“Enter ID #: ”); scanf(“%u”, &s.ID); printf(“Enter GPA: ”); scanf(“%lf”, &s.GPA); return s; } ECE Application Programming: Lecture 27

  9. Nested structures • Structures can contain other structures: typedefstruct { char first[50]; // First name char middle; // Middle initial char last[50]; // Last name } Name; typedefstruct { Name sname; // Student name unsigned int ID; // ID # double GPA; // Grade point } SINew; • Will need multiple dot operators to access field within nested structure • Given SINew s1; • s1.sname  Name structure within s1 • s1.sname.middle  middle initial of name within s1 ECE Application Programming: Lecture 27

  10. PE4 (Structures) • Given header files, main program • Complete specified functions • For the Name structure • void printName(Name *n): Print the name pointed to by n, using format <first> <middle>. <last> • void readName(Name *n): Prompt for and read a first, middle, and last name, and store them in the structure pointed to by n • SINew functions on next slide ECE Application Programming: Lecture 27

  11. Today’s exercise (continued) • Given header files, main program • Complete specified functions • Name functions on previous slide • For the SINewstructure • void printStudent(SINew *s): Print information about the student pointed to by s • void readStudent(SINew *s): Prompt for and read information into the student pointed to by s • void printList(SINew list[], int n): Print the contents of an array list that contains nStudentInfo structures • intfindByLName(SINew list[], int n, char lname[]): Search for the student with last name lname in the array list. Return the index of the structure containing that last name, or -1 if not found • intfindByID(SINew list[], int n, unsigned intsID): Search for the student with ID # sID in the array list. Return the index of the structure containing that last name, or -1 if not found ECE Application Programming: Lecture 27

  12. Next time • Finish PE4 • File I/O • Reminders: • Program 6 graded; regrades due 11/29 • Program 7 posted; due 11/20 • Programs submitted 11/21-11/26 “1 day late” • Late penalties begin increasing again on 11/27 ECE Application Programming: Lecture 27

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