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Variables and TypesThe buildings blocks of apps

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Coffee

=+

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Coffee

•17 ml water : 1 g coffee

•950 ml water / 17 ml/g = ?

•55.8 g coffee

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VariablesGive the CPU something to remember

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// Declare a variable to store waterfloat water;

// Store the amount of water to usewater = 950; // milliliters

// Display messageprintf("Brew %f milliliters of coffee", water);

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int age = 26;

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int age = 26;type

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int age = 26;type name

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int age = 26;type name expression

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int age = 26;type name expression

assignmentoperator

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int age = 26;

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int age = 26;

26age

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

a

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

a

b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b; b

5a

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

5a

20b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

5a

205+b

b

Paul Solt iPhoneDev.tv

int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

5a

205+20

b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

5a

255+20

b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

5a

25b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

5a-b

a

25b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

55-25

a

25b

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int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

-205-25

a

25b

Paul Solt iPhoneDev.tv

int a;int b;a = 5;b = 20;b = 5 + b;a = a - b;

-20a

25b

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TypesWhat kind of information are we storing?

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•short/int/long: -1,0,1•float/double: 3.14•char: ‘a’, ‘b’, ‘c’•pointers: int * (memory address)•struct: composition (x, y)

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short small = 12;int medium = 2000000;long large = 90133726844735000;

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float smaller = 3.14;double larger = 3.14159265359;

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char firstLetter = 'a';char percent = '%';

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0 18

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0 18

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544&x

0 18

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0x5544

&x

18

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0x5544

&x

18

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0x5544 18*address

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0x5544 27*address

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int *address = 0;int x = 18;address = &x;*address = 27;

address x

0x1234 0x5544

0x5544 27

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struct Point { int x; int y;};

...

struct Point a;a.x = 25;a.y = 100;

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struct Point { int x; int y;};

...

struct Point a;a.x = 25;a.y = 100;

(25, 100)y

x

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•short/int/long: -1,0,1•float/double: 3.14•char: ‘a’, ‘b’, ‘c’•pointers: int * (memory address)•struct: composition (x, y)

Paul Solt iPhoneDev.tv