Bài giảng lập trình c 2010 chương 3 đh công nghệ đồng nai

DONG NAI UNIVERSITY OF TECHNOLOGY


Format Code
Format

2

DONG NAI UNIVERSITY OF TECHNOLOGY

Description

Code

C or c

Formats the string as currency. Precedes the number with
an appropriate currency symbol ($ in the US).

D or d

Formats the string as a decimal. Displays number as an
integer.

N or n

Formats the string with commas and two decimal places.


Format Code
Format

3

DONG NAI UNIVERSITY OF TECHNOLOGY

Description

Code
E or e

Formats the number using scientific notation with a default of
six decimal places

F or f

Formats the string with a fixed number of decimal places (two
by default).

G or g

General. Either E or F.

X or x

Formats the string as hexadecimal.


DONG NAI UNIVERSITY OF TECHNOLOGY

DONG NAI UNIVERSITY OF TECHNOLOGY

Logical and
Conditional Operators


DONG NAI UNIVERSITY OF TECHNOLOGY

1

2

Logical

Conditional AND (&&)

AND(&)
3

4

Logical OR (|)

5

Logical exclusive OR
or XOR (^)

Conditional OR (||)

6

Logical NOT (!)


DONG NAI UNIVERSITY OF TECHNOLOGY

Used to add multiple
conditions to a statement


DONG NAI UNIVERSITY OF TECHNOLOGY

exp1

exp2

exp1 && exp2

false

false

false

false

true

false

true

false

false

true

true

true

Truth table for the && (logical AND)
operator.


DONG NAI UNIVERSITY OF TECHNOLOGY

Exp1

exp2

exp1 || exp2

false

false

false

false

true

true

true

false

true

true

true

True

Truth table for the || (logical OR) operator.


DONG NAI UNIVERSITY OF TECHNOLOGY

exp1

exp2

exp1 ^ exp2

false

false

false

false

true

true

true

false

true

true

true

false

Truth table for the logical exclusive OR (^)
operator.


DONG NAI UNIVERSITY OF TECHNOLOGY

expression

!expression

false

true

True

false

Truth table for operator! (logical NOT).


DONG NAI UNIVERSITY OF TECHNOLOGY

Control Structures

• Program of control
–Program performs one statement then goes to next
line

•Sequential execution


DONG NAI UNIVERSITY OF TECHNOLOGY

– Different statement other than the next one executes
• Selection structure

–The if and if/else statements
• Repetition structure
–The while and do/while loops
–The for and foreach loops


DONG NAI UNIVERSITY OF TECHNOLOGY

total = total + grade;
add grade to
total
counter = counter + 1;
add 1 to counter

Flowcharting C#’s sequence structure.


DONG NAI UNIVERSITY OF TECHNOLOGY

if Selection Structure




Causes the program to make a selection
Chooses based on conditional

•
•
•




Any expression that evaluates to a bool type
True: perform an action
False: skip the action

Single entry/exit point
Require no semicolon in syntax


DONG NAI UNIVERSITY OF TECHNOLOGY

if Selection Structure

true
conditions

false

do something


DONG NAI UNIVERSITY OF TECHNOLOGY

If/else Selection Structure







Alternate courses can be taken when the statement is false
Rather than one action there are two choices
Nested structures can test many cases
Structures with many lines of code need braces ({)

•

Can cause errors




Fatal logic error
Nonfatal logic error


DONG NAI UNIVERSITY OF TECHNOLOGY

If/else Selection Structure

false

true
Conditions

do something else

do something

DONG NAI UNIVERSITY OF TECHNOLOGY

Conditional Operator (?:)
C#’s only ternary operator
Similar to an if/else structure
The syntax is:
booleanvalue
value??ififtrue
true::ififfalse
false
boolean
MessageBox.Show(dtb>=5?“Dau”:
“Dau”:“Rot”);
“Rot”);
MessageBox.Show(dtb>=5?


DONG NAI UNIVERSITY OF TECHNOLOGY

Loops





Repeating a series of instructions
Each repetition is called an iteration
Types of Loops

o

Do


o

Use when the number of iterations is unknown

For



Use when the number of iterations known


DONG NAI UNIVERSITY OF TECHNOLOGY

while Repetition Structure

true
conditions

false

do something


DONG NAI UNIVERSITY OF TECHNOLOGY

for Repetition Structure

• The for repetition structure
– Syntax: for (Expression1, Expression2, Expression3)
• Expression1 = names the control variable
– Can contain several variables
• Expression2 = loop-continuation condition
• Expression3 = incrementing/decrementing
– If Expression1 has several variables, Expression3
must have several variables accordingly

– ++counter and counter++ are equivalent
– Variable scope
• Expression1 can only be used in the body of the for loop
• When the loop ends the variable expires


DONG NAI UNIVERSITY OF TECHNOLOGY

for Repetition Structure
Final value
for

of control variable

keyword
Control variable

for ( int

Initial value

name

i = 1; i <= 5; i++ )

of control variable

Loop-continuation condition
Increment

of control variable


DONG NAI UNIVERSITY OF TECHNOLOGY

for Repetition Structure
Establish initial value of control
variable.
int counter = 1

Determine if final value of
control variable has been
reached.

true

Console.WriteLine

counter <= 10

counter++
( counter * 10 );

Increment the
false

Body of loop (this may be
multiple statements)

control variable.


DONG NAI UNIVERSITY OF TECHNOLOGY

switch Multiple-Selection Structure

•

The switch statement

– Constant expressions
• String
• Integral
– Cases
• Case ‘x’ :
– Use of constant variable cases
• Empty cases
• The default case

– The break statement
• Exit the switch statement