1. 16.216 ECE Application Programming
Instructor: Dr. Michael Geiger
Spring 2012
Lecture 38: Exam 3 Preview

2. ECE Application Programming: Lecture 38
Lecture outline
Announcements/reminders
Final exam: Tues., 5/15, 8:00-11:00 AM, Ball 314
Program 9 due today
No regrades, late submissions allowed
If submitted, will replace your lowest grade
Program grading (mostly) up to date
All penalty-free regrades due 11:59 PM today unless otherwise noted
Course evaluations
Excused students
Exam 3 Preview
General exam info
Topics covered
One-dimensional arrays
Pointer arithmetic
Strings
Two-dimensional arrays
File I/O
Structures
11/26/2017
ECE Application Programming: Lecture 38

3. ECE Application Programming: Lecture 38
Excused students
The following students are excused from the final exam (after completing a course evaluation)
Chheou, Dy
Citta, Timothy
Dongo, Mario
Hajj, Andrew
Haoui, Ali
Khuu, Jonathan
Miskell, Timothy
Muse, Bradley
Pflanz, Timothy
Pham, Philip
Taku, Jonathan
Tan, Yushi
Wall, Bradley
11/26/2017
ECE Application Programming: Lecture 38

4. ECE Application Programming: Lecture 38
Exam 3 notes
Q & A session 5/14—what times work best?
Allowed one 8.5” x 11” two-sided note sheet
No other notes or electronic devices
Exam lasts 3 hours (but is written for ~50 min)
Covers all lectures after Exam 2 (lec )
Format similar to Exams 1/2
1 multiple choice problem (File I/O & structures)
1 code reading problem
1 code writing problem
Practice problems posted; can also look at old exams
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ECE Application Programming: Lecture 38

5. Review: arrays & pointer arithmetic
Arrays: groups of data with same type
x[10] has 10 elements, x[0] through x[9]
Can also define with initial values
e.g. double list[] = {1.2, 0.75, };
Must be sure to access inside bounds
Array name is a pointer
Arrays are always passed by address to functions
Can use pointer to access array
Can use arithmetic to move pointer through array
p + 1  points to next element (after where p currently points)
p++  move pointer and point to next element
p--  move pointer and point to previous element
11/26/2017
ECE Application Programming: Lecture 38

6. ECE Application Programming: Lecture 38
Review: strings
Represented as character arrays
Can be initialized using string constants
char hello[] = “Hello”;
Can access individual elements
hello[3] = ‘l’;
Can print directly or with formatting
Print directly: printf(hello);
Print w/formatting using %s: printf(“%s\n”, hello);
Must leave enough room for terminating ‘\0’
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ECE Application Programming: Lecture 38

7. Review: String functions
In <string.h> library:
Copying strings:
char *strcpy(char *dest,
const char *source);
char *strncpy(char *dest,
const char *source,
size_t num);
Return dest
Comparing strings:
int strcmp(const char *s1, const char *s2);
int strncmp(const char *s1, const char *s2, size_t num);
Character-by-character comparison of character values
Returns 0 if s1 == s2, 1 if s1 > s2, -1 if s1 < s2
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ECE Application Programming: Lecture 38

8. Review: String functions (cont.)
Find # of characters in a string
size_t strlen(const char *s1);
Returns # characters before ‘\0’
Not necessarily size of array
“Add” strings together—string concatenation
char *strcat(char *dest,
const char *source);
char *strncat(char *dest,
const char *source,
size_t num);
Returns dest
11/26/2017
ECE Application Programming: Lecture 38

9. ECE Application Programming: Lecture 38
Review: 2D arrays
Declared similarly to 1D arrays
Example (see below): int x[3][4];
Index elements similarly to 1-D arrays
Initialize: int y[3][4] =
{ {1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12} };
Typically used with nested for loops
Can pass to functions—must specify # columns
Col. 0
Col. 1
Col. 2
Col. 3
Row 0
x[0][0]
x[0][1]
x[0][2]
x[0][3]
Row 1
x[1][0]
x[1][1]
x[1][2]
x[1][3]
Row 2
x[2][0]
x[2][1]
x[2][2]
x[2][3]
11/26/2017
ECE Application Programming: Lecture 38

10. ECE Application Programming: Lecture 38
Review: File I/O
Open file: FILE *fopen(filename, file_access)
Close file: fclose(file_handle)
Formatted I/O:
fprintf(file_handle, format_specifier, 0+ variables)
fscanf(file_handle, format_specifier, 0+ variables)
Unformatted I/O:
size_t fwrite(pointer, element size, # elements, file_handle)
size_t fread(pointer, element size, # elements, file_handle)
Check for EOF using either fscanf() result or feof(FILE *)
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ECE Application Programming: Lecture 38

11. Review: Unformatted I/O (cont.)
Character I/O
int fputc(int c, FILE *stream);
int putchar(int c);
int fgetc(FILE *stream);
int getchar();
int ungetc(int c, FILE *stream);
Line I/O
int fputs(const char *s, FILE *stream);
int puts(const char *s);
char *fgets(char *s, int n, FILE *stream);
char *gets(char *s);
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ECE Application Programming: Lecture 35

12. ECE Application Programming: Lecture 38
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;
Access members using
Dot operator: student1.middle = ‘J’;
Arrow (if pointers): sPtr->GPA = 3.5;
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ECE Application Programming: Lecture 38

13. ECE Application Programming: Lecture 38
Next time
Exam 3: Tues. 5/15, 8:00-11:00 AM
11/26/2017
ECE Application Programming: Lecture 38