1. EECE.2160 ECE Application Programming
Instructor:
Dr. Michael Geiger
Fall 2018
Lecture 25
Exam 2 Preview

2. ECE Application Programming: Exam 2 Preview
Lecture outline
Announcements/reminders
Exam 2 in class Monday, 11/5
Will be allowed one 8.5” x 11” note sheet
Will cover lectures (except lecture 16)
Please attend the section for which you are registered
Program 5 due 11/7
Program 4 regrades due 11/9
Today’s lecture: Exam 2 Preview
7/2/2019
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 material starting after Exam 1, through lecture 24 (lectures 14-24, except 16)
Same general format as Exam 1
3 sections (each with multiple parts, so ~10 questions) + 1 extra credit question
For loops (in all sections)
Functions (code reading/writing)
Arrays (code reading/writing, MC)
Strings (MC)
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ECE Application Programming: Exam 2 Preview

4. ECE Application Programming: Exam 2 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
Don’t worry about pre-/post-increment differences for test
7/2/2019
ECE Application Programming: Exam 2 Preview

5. ECE Application Programming: Exam 2 Preview
Review: functions
Key points to understand
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—allows function to change >1 value
Return value
Expression following return keyword
Value copied back to where function is called
Can be assigned to variable, used in another expression, etc.
7/2/2019
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
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ECE Application Programming: Exam 2 Preview

7. Review: pass by value; return value
int f(int x, int y) { x = x + 2; // Change x only // inside function return (x + y) / 2; } int main() { int a = 10; int b = 20; int c = f(a, b); // Given f() … // above, c = 16 printf("%d", f(5, 15)); // Prints 11 … // (return // val. of f)
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ECE Application Programming: Exam 2 Preview

8. Review: pass by address
int f2(int *p1, int *p2) { *p1 = *p1 + 2; *p2 = *p2 – 3; return *p1 + *p2; } int main() { int a = 10; int b = 20; int c = f2(&a, &b); // a = a + 2 = 12 // b = b – 3 = 17 // c = a + b = 29
7/2/2019
ECE Application Programming: Exam 2 Preview

9. 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
Should pass size of array as additional argument
e.g. void f(int arr[], int n);
7/2/2019
ECE Application Programming: Exam 2 Preview

10. 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
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]
7/2/2019
ECE Application Programming: Exam 2 Preview

11. 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);
Reading strings: scanf(“%s”, str);
Reads all characters up to (but not including) first space, tab, or newline
Must leave enough room for terminating ‘\0’
7/2/2019
ECE Application Programming: Exam 2 Preview

12. 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
strncpy() not guaranteed to add null terminator
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, non-zero value if s1 != s2
7/2/2019
ECE Application Programming: Exam 2 Preview

13. 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
strncat() guaranteed to add null terminator
7/2/2019
ECE Application Programming: Exam 2 Preview

14. ECE Application Programming: Exam 2 Preview
Final notes
Next time: Exam 2
Please be on time
Please attend the section for which you are registered
Reminders:
Program 5 due 11/7
Program 4 regrades due 11/9
7/2/2019
ECE Application Programming: Exam 2 Preview