1. Exercise 6 – Compound Types und Kontrollfluss
Informatik I / D-ITET
Informatik I / D-ITET
Exercise 6 – Compound Types und Kontrollfluss 1

2. Agenda
Structures
Unions
Enumerations
Loops (for, while, do while)

3. Structures Structures are user-defined Types Variable declaration:
Type definition:
Variable declaration:
Accessing member variables:
struct MyNewDataType { member_type1 member1; member_type2 member2; };
MyNewDataType myNewDataObject;
myNewDataObject.member1 = ...;

4. Structures Definition Initialization Assignment
struct MyStruct{ int i; float f; };
MyStruct m1;
MyStruct m2 = {1, 2.0f};
m1 = m2; // m1.i = m2.i; m1.f = m2.f;

5. Structures Nesting Type of member variables can be arbitrary
Self-defined types can also be used
Example:
No recursive nesting (no Date struct inside another Date)!
Recursive data structures later in course
struct Date{ int day; int month; int year; };
struct Person { Date birthday; string name; int age; };

6. Unions Definition Initialization
If they don‘t have the same size, the union takes the size of the biggest element
Values of the union array after initialization:
union MyUnion{ char c[4]; // On the same memory int i; // On the same memory };
c[3]
c[2]
c[1]
c[0]
MyUnion u1;
u1.i = 1;
I = 0x
c[0] == 1, c[1] == 0, c[2] == 0, c[3] == 0

7. Enumerations Definition Assignment is limited:
enum Months{January, February, March};
enum Months{January = 1, February, March};
enum Months{January = 1, June = 6, March = 3};
int a = February;
Months a = 2; // ERROR

8. Loops - Overview
for loops
while loops
do – while loops

9. for Loop Declare and initialize loop variable:
Check continue condition BEFORE:
Increment AFTER loop
int i=0;
i < 4;
i++
for (int i=0; i < 4; i++)
{ cout << “i is: “ << i; }
Sidenote: Shown here is the C99 standard. Older C-code might require this: int i; for (i=0; i < 4; i++)

10. while Loop Declare and initialize loop variable:
Check continue condition BEFORE:
Increment AFTER loop
int i=0;
i < 4;
i++
int i=0;
while (i < 4)
{ cout << “i is: “ << i;
i++; }

11. For and While Comparison
int i;
for (i=0; i < 4; i++)
{ cout << “i is: “ << i; }
For and while can be used equivalently
Loop variable i stays valid after the loop if declared outside of braces
For loops for known length iteration
While loops to loop until complex condition is met
int i=0;
while (i < 4)
{ cout << “i is: “ << i;
i++; }

12. do while Loop Declare and initialize loop variable:
Check continue condition AFTER:
Increment AFTER loop
int i=0;
i < 4;
i++
int i=0;
do { cout << “i is: “ << i;
i++;
} while (i < 4);