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

Format CodeFormat Code Description C or c Formats the string as currency.. Format CodeFormat Code Description E or e Formats the number using scientific notation with a default of six

Format Code

Format

Code

Description

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

Code

Description

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.

Logical and Conditional Operators

Logical AND( & )

Conditional AND ( && )

Used to add multiple

conditions to a statement

exp1 exp2 exp1 && exp2

false false false

true false false

(logical AND) operator.

Exp1 exp2 exp1 ||

exp2

(logical OR) operator.

exp1 exp2 exp1 ^ exp2

false false false

Truth table for the logical

Control Structures

• Program of control

–Program performs one

statement then goes to next

line

•Sequential execution

–Different statement other than the

next one executes

Flowcharting C#’s sequence structure.

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

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

If/else Selection Structure

Conditions

do something

do something else

Conditional Operator ( ? :)

C#’s only ternary operator

Similar to an if/else structure

The syntax is:

boolean value ? if true : if false

boolean value ? if true : if false

MessageBox.Show(dtb>=5?

“Dau”: “Rot”);

MessageBox.Show(dtb>=5?

“Dau”: “Rot”);

 Repeating a series of instructions

 Each repetition is called an iteration

while Repetition Structure

true

false

do something

conditions

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

• Expression1 can only be used in the body of the for loop

• When the loop ends the variable expires

for Repetition Structure

for ( int i = 1; i <= 5; i++ )

Initial value of control variable

Increment of control variable

Control variable name

Final value of control variable

for keyword

Loop-continuation condition

for Repetition Structure

variable has been

reached. counter <= 10 Console.WriteLine

statements)

Increment

the control variable.

switch Multiple-Selection Structure

• The switch statement

– Constant expressions

• String

• Integral – Cases

switch Multiple-Selection Structure

break;

case : a true case a action(s)

false

.

do/while Repetition Structure

• The while loops vs the do/while loops

– Using a while loop

• Condition is tested

• The the action is performed

• Loop could be skipped altogether – Using a do/while loop

• Action is performed

• Then the loop condition is tested

• Loop must be run though once

• Always uses brackets ({) to prevent confusion

do/while Repetition Structure

5

do/while Repetition Structure

true false

action(s)

condition

Statements break and continue

• Use

– Used to alter the flow of control

– The break statement

• Used to exit a loop early – The continue statement

• Used to skip the rest of the statements and begin the loop at the first statement in the loop

– Programs can be completed without their usage

Handle Exception

• An exception occurs when a program encounters any unexpected problems.

• Your program should be able to

handle these exceptional situations

and, if possible, gracefully recover

from them This is called exception

handling

The throw statement

if (n < 0)

{

ArithmeticException ex1 =

finally Block

The finally block contains code that always

executes, whether or not any exception occurs

class CMyException : ApplicationException

{

}

Error provider

bool bValid = true ;

bool bValid = true ;

bool bValid = true ;

if

(dateTimePicker1.Value.DayOfWeek

errorProvider1.SetError (dateTimePicker1

}

}

btnDangKy_Click( object sender,

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