1. Module 2 Variables, Data Types and Arithmetic

2. Naming Rules and Conventions
Contain only letters, digits and underscore
Cannot begin with a digit
Are case-sensitive
Begin with lowercase
Do not begin with underscore
Multi-word variables
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Keywords
Commonly used keywords
break
double
goto
short
typedef
case
else if
signed
union
char
enum
int
sizeof
unsigned
continue
extern
long
static
void
default
float
register
struct
while do
for
return
switch
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Other Rules
Variables may be declared anywhere in your code, but must be declared before they are used
Global variables are permitted and declared outside of any block
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Basic Data Types
int
integer values, no decimal point
float
floating point values with decimal part
double
same as float, but more precision
char
a single character
_Bool
boolean values 0 (false) and 1 (true)
This a C99 data type addition
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Type Specifiers
long
Applied to int to give a (possibly) larger range of values
Also applicable to double
long long
Applied to int to give an even larger range of values
short
Applied to int to (possibly) limit the range of values
unsigned
Applied to int to indicate only zero and positive values
signed (default type)
Applied to int to specify positive, negative and zero values allowed
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Integral Data Types
The table below shows the usual sizes and ranges of the integral data types on a 32-bit machine
Your sizes and ranges may vary
Data Type
Size (in bytes)
Range of values
signed short int 2
to 32767
unsigned short int
0 to 65535
signed int 4 to
unsigned int
0 to
signed long int
unsigned long int
signed long long int 8
-9 x 1018 to 9 x 1018
unsigned long long int
0 to 18 x 1018
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8. Floating Point Data Types
The table below shows the usual sizes and ranges of the floating point data types on a 32-bit machine
Your sizes and ranges may vary
Data Type
Size (in bytes)
Precision
Values
float 4
Approximately 6 digits
Approximately -10^38 to 10^38
double 8
Approximately 15 digits
Approximately -10^308 to 10^308
long double
Machine Dependent
Even more precision
???
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Booleans
Data type: _Bool
Size in bytes: (probably) 1
Range of values: 0 , 1
stdbool.h
Defines bool data type
Defines true and false
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Literal Constants
Decimal (base 10) integer constant L
Octal (base 8) constant
0173
Hexadecimal (base 16) constant
0x12F4C
Floating Point constant
e-2
String constant
“Hello World”
Character constant
‘z’ ‘\n’
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Named Constants
#define preprocessor directive
Literal string substitution
#define VOTING_AGE 18
#define GREETING “Hello!”
#define PI
#define QUIT ‘q’
Typically DO NOT end with semi-colon
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Exercises
Questions
Text pg 40 - #2, #3
Just write down your answers
They do not involve coding
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13. Variable Declarations
int height = 72; long maxNumberOfPassengers; char middleInitial = ‘L’, newLine = ‘\n’; double averageScore = 0.0; unsigned int nrRows = 5, nrColumns = 10; short average;
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14. Displaying Basic Types
printf characters for basic type output
Integers
%d, %i
%u (unsigned)
Floating Point
%f – default (6 decimal places)
%e – scientific notation
%g – automatically chooses between %f and %e format
Characters
%c – a single character
Booleans
%d, %i, %u
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In-Class Example
VarBasicOutput project
Look at floatingVar and it’s results
Also look at the boolean output as an integer
what’s the difference between %d and %i
pg 26 in book
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Operator Definitions
Operand
An expression which is manipulated by an operator
Operator
A symbol that represents the action to be taken
Unary, Binary or Ternary
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In-Class Example
VarDataDemo project
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Arithmetic
Addition x = ; y = z + w;
Subtraction x = 3.7 – 2; d = 5 – z;
Multiplication x = 3.6 * 2.5; x = 5 * y;
Division x = 3 / 2; x = 3 / 2.0;
Modulus x = 3 % 2; y = z % 6;
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Exploring Division
Integer Division
int / int int 3 / 2 = 1
Floating point division
float / float float 3.0 / 2.0 = 1.5
Mixed Division
int / float float 3 / 2.0 = 1.5
float / int float 3.0 / 2 = 1.5
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Type Conversion
int i1, i2 = -150; float f1 = , f2; i1 = f1; f1 = i2; f1 = i2 / 100; f2 = i2 / 100.0; f2 = (float)i2 / 100;
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Binary Operators
Two operands
x = x + 5 ;
y = y * 6;
z = z – (x + 2);
Shortcut notation
x += 5;
y *= 6;
z -= x + 2;
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Pre/post-increment
x++ (post-increment)
int z, x = 5;
x++;
z = 3 * x++;
++x (pre-increment)
++x;
z = 3 * ++x;
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Pre/post-decrement
x-- (post-decrement)
int z, x = 5;
x--
z = 3 * x--
--x (pre-decrement)
--x;
z = 3 * --x;
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24. Precedence and Associativity
Level
Operators
Associativity
Operation 1
() expr++,expr --
L R
Parentheses 2
++expr, --expr
R L
Unary Operators 3
+,- 4
*, /, %
Binary Operators 5
+, - 6
=, -=, +=,
-=, *=, /=, %=
Assignment operators
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In-Class Exercises
Solve these expressions
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Lab Exercises
Text Questions pg 40 #1
not all
do first one, then another of your choice
#2-8
Ex1-ArithmeticPractice.docx—from CMSC 201
Ex2-Coins.docx – quarters, nickels, dime, pennies to dollars and cents
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