1. 16.216 ECE Application Programming
Instructor: Dr. Michael Geiger
Spring 2014
Lecture 24
Exam 2 Preview

2. ECE Application Programming: Exam 2 Preview
Lecture outline
Announcements/reminders
Program 7 posted; due 4/9
Exam 2: Wednesday, 4/2
Allowed one 8.5” x 11” sheet of notes
Today’s lecture: Exam 2 Preview
4/28/2018
ECE Application Programming: Exam 2 Preview

3. ECE Application Programming: Exam 2 Preview
Exam 2 notes
Allowed one 8.5” x 11” double-sided note sheet
No other notes
No electronic devices (calculator, phone, etc.)
Exam will last 50 minutes
Covers all lectures after Exam 1 (13-22) except Friday’s lecture on file I/O
Same general format as Exam 1
1 multiple choice
1 code reading
1 code writing (complete 2 of 3 parts; all 3 for extra credit)
4/28/2018
ECE Application Programming: Exam 2 Preview

4. ECE Application Programming: Exam 1 Preview
Review: for loops
for (<init var>; <test>; <change var>)
<statements>
Operators to directly change variable
x++, x--  post-increment/decrement
++x, --x  pre-increment/decrement
+=, -=, *=, /=  augmented assignment
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ECE Application Programming: Exam 1 Preview

5. ECE Application Programming: Exam 2 Preview
Review: functions
Used to break programs into smaller pieces
Useful when code sequences repeated
Functions have:
An optional return value
A name
Optional arguments
Must be prototyped or written completely prior to use
Arguments can be:
Passed by value: copy of argument is sent to function
Arguments cannot be modified outside function
Passed by address: address of argument
Use pointers or address operator (&)
Arguments can be modified outside function—used to “return” multiple values
4/28/2018
ECE Application Programming: Exam 2 Preview

6. ECE Application Programming: Exam 2 Preview
Review: pointers
Pointer: address of a variable
Can get address of existing object using &
Can get value of existing pointer using *
Can assign pointers of same type to each other
Pointer declaration:
<base type>* <pointer name>
Base type determines how reference is interpreted
Use pointers as function arguments  pass by address
4/28/2018
ECE Application Programming: Exam 2 Preview

7. Review: arrays & pointers
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
We will not cover pointer arithmetic on this exam
4/28/2018
ECE Application Programming: Exam 2 Preview

8. ECE Application Programming: Exam 2 Preview
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]
4/28/2018
ECE Application Programming: Exam 2 Preview

9. ECE Application Programming: Exam 2 Preview
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’
4/28/2018
ECE Application Programming: Exam 2 Preview

10. 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
4/28/2018
ECE Application Programming: Exam 2 Preview

11. 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
4/28/2018
ECE Application Programming: Exam 2 Preview

12. ECE Application Programming: Exam 2 Preview
Final notes
Next time
Exam 2—please be on time
Reminders:
Program 7 posted; due 4/9
Exam 2: Wednesday, 4/2
Allowed one 8.5” x 11” sheet of notes
4/28/2018
ECE Application Programming: Exam 2 Preview