886201 หลั�กการโปรแกรม 1Lecture 9: การทำ าซ้ำ �า (for)

ทบทวนเรื่��อง while

ทบทวนเรื่��อง do-while

The for Statement•Syntax

for (ForInit ; ForExpression; PostExpression)

Action

•Examplefor ( int i = 0; i < 3; i++ )

{ cout << “i is " << i

<< endl;}

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i 0

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i 0

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0

i 0

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0

i 0

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0

i 1

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i 1

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1

i 1

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1

i 1

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1

i 2

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1

i 2

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1i is 2

i 2

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1i is 2

i 2

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1i is 2

i 3

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1i is 2

i 3

Execution Trace

for (int i = 0; i < 3; ++i) {cout << "i is " << i << endl;}cout << "all done" << endl;

i is 0i is 1i is 2all done

i 3

Example: หาผลัรวมของเลัข 1 ถึ�ง 10

T

F

i=i+1

i<=10

sum = sum+i

i = 1

sum = 0

sum = 0;

for (int i=1; i <= 10; i++ )

sum += i;

RESULT:sum =1+2+3+...+10

Example: พิ�มพิ�เลัขคี่��ทำ��อยู่� ในช่ วง 1 ถึ�ง 10

T

F

i+=2

i < 10

i = 1

print i

for (int i=1; i<10;

i+=2)

cout << i << “ ”;

RESULT:

1 3 5 7 9

Example: พิ�มพิ�คี่ า 10 ลังมาจนถึ�ง 1

i = 10

print i

i=i-1

T

Fi>=1

for (int i=10; i >= 1; i--)

cout << i << “ ”;

initialization condition statements update

for (int count = 1; count <= 10; count++){ cout << count << endl;}

int count = 1; // Initialize the counterwhile (count <= 10) // Check the counter{ cout << count << endl;

count++; // Update the counter}

initialization condition statements update

while vs. for

แบบฝึ�กหั�ด• ให%เข�ยู่นโปรแกรมเพิ&�อแสดงคี่ า x2 + x – 4 เม&�อ x=5, 6, …,12

• ให%เข�ยู่นโปรแกรมเพิ&�อแสดงส�ตรคี่�ณแม 5