LOOP (Part 2) for while do-while 1. TK1913-C Programming2 TK1913-C Programming 2 Loop : for Loop :...

LOOPLOOP(Part 2)(Part 2)

forwhile

do-while

1

TK1913-C ProgrammingTK1913-C Programming 22

Loop : Loop : forfor

Condition is tested first Loop is controlled by a counter Syntaxes

for (initial value ; condition; update counter) statement;

Or

for (initial value ; condition; update counter) {statement;statement;

}


ExampleExample

Write a program which does the following:

Reads 5 integers and displays the sum of all

integers

Input example: 3 6 4 1 2

Output example: 16


Recall the flowchartRecall the flowchart

counter ← 1, sum ← 0

counter < 6

sum←sum+ x

false

true

counter++

output sum

input x


Note the initial Note the initial value of ivalue of i

and conditionand condition

i ← 1, sum ← 0

i < 6

sum←sum+ x

false

true

i++

output sum

input xHow many times How many times does the loop get does the loop get

executed? executed?


i ← 0, sum ← 0

i < 6

sum←sum+ x

false

true

i++

output sum


executed? executed?


i ← 0, sum ← 0

i < 5

sum←sum+ x

false

true

i++

output sum


executed? executed?


The C statements:

int x, sum, i;sum = 0;for (i = 0; i < 5; i++) {

scanf(“%d”,&x);sum = sum + x;

}printf(“%d”,sum);


i ← 0, sum ← 0

i < 5

sum←sum+ x

false

true

i++

output sum

input x

int x, sum, i;sum = 0;for (i = 0; i < 5; i++) {

scanf(“%d”,&x);sum = sum + x;

}printf(“%d”,sum);


forfor statement statement

Example:

for ( num = 1; num <= 3; num++ ) printf(“%d\t”, num);

num

???

_

1 _


Example:

for (num = 1; num <= 3; num++ ) printf(“%d\t”, num);

num

1

_



Example:


num

1

_



Example:


num

1

1 _



Example:


num

2

1 _




Example:


bil

2

1 2 _


Example:


num

3

1 2 _



Example:


num

3

1 2 3 _



Example:


num

4

1 2 3 _



forwhile

do-while


Loop: whileLoop: while

Condition is tested first Loop is controlled by condition or a counter Syntax

while (condition) statement;

Orwhile (condition) {

statement;statement;

}


Recall this example:

Given an exam marks as input, display the appropriate message based on the rules below:

If marks is greater than 49, display “PASS”, otherwise display “FAIL”

However, for input outside the 0-100 range, display “WRONG INPUT” and prompt

the user to input again until a valid input is entered


false

true

input m

m<0 || m>100

m>49 “PASS”

“FAIL”

true

false

“WRONG INPUT”

input m

Exercise:

Convert this flowchart to a C program


int marks;scanf(“%d”,&marks);while (marks<0) | | (marks>100) {

printf(“WRONG INPUT”);scanf(“%d”,&marks);

}if (marks>49) {

printf(“PASS”);else

printf(“FAIL”);}

DoubleSelection


ExerciseExercise Given a set of integers

with the last one being 999 Display the summation of

all the integers.

Input example: 1 3 23 999

Output example: Sum = 27

Draw the flowchart for this problem


Sentinel-controlled loop

true

x!=999

sum←sum+x

false

input x

sum=0

input x

output sum

#include <stdio.h>

void main() {

int sum, x;

sum = 0;

scanf(“%d”, &x);

while (x != 999) {

sum = sum + x;

scanf(“%d”, &x);

}

printf(“The sum : %d\n”, sum);

}


int sum, x; sum = 0; scanf(“%d”, &x); while (x != 999) { sum = sum + x; scanf(“%d”, &x); } printf(“\nThe sum : %d\n”, sum);

?

?x

sum 0

1

_1

1 != 999

0+11

1 3

33 != 999

1+34

1 3 23

2323 != 999

4+2327

1 3 23 999

999999 != 999

The sum : 27


Do-while LoopDo-while Loop Statements in the loop are executed first (at least

onc, and condition is tested last Loop is controlled by a condition or counter Syntax

do { statement;statement;

} while (condition);statement;


do-while statementdo-while statement

Example :printf(“Input start and end value : “);scanf(“%d %d”, &start, &end);do {

printf(“%c (%d)\n“, start, start);start++;

} while (start <= end) ;

_

???

start

???

end

Input start and end value : _Input start and end value : 65 67_

65 67

Input start and end value : 65 67A (65)_

66

66 <= 67

Input start and end value : 65 67A (65)B (66)_

67 <= 67

67

Input start and end value : 65 67A (65)B (66)C (67)_

68

68 <= 67


continuecontinue statement statement

Example:

for ( i = 0; i <= 5; i++ ) { if ( i % 2 )

continue; else

printf(“%d is an even number. ”, i); printf(“Print iff even ! \n”);}

i i <= 5 i % 2

_

0 0 <= 9 true 01 <= 5 true1 2 <= 5 true3 <= 5 true4 <= 5 true5 5 <= 5 true 16 6 <= 5 false234 1010

0 is an even number._0 is an even number. Print iff even !

_

0 is an even number. Print iff even !

2 is an even number._



_



4 is an even number._




_


Now what can you conclude about continue?


breakbreak statement statement

printf(“Input a value between 1 – 7: ”);scanf(“%d”,&value);for (i = 1; i <= 7; i++) {

if ( i = = value ) break;printf(“\n%d”,i);

}printf(“YeePee! I’m out of the loop!\n”);

value

???

i i <= 7 i == value

Input a value between 1-7: _Input a value between 1-7: 4

1 1 <= 7 true 1 == 4 false

4

Input a value between 1-7: 4

1

2 2 <= 7 true 2 == 4 false


1

2

3 3 <= 7 true 3 == 4 false


1

2

3

4 4 <= 7 true 4 == 4 true


1

2

3YeePee! I’m out of the loop!


Now what can you conclude about

break?


End of 1End of 1stst half of the semester half of the semester

Yes !! That’s all? Yes !! That’s all? What’s next???What’s next???

1 week HOLIDAY1 week HOLIDAYon the way … on the way …

LOOP (Part 2) for while do-while 1. TK1913-C Programming2 TK1913-C Programming 2 Loop : for Loop :...

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