This document discusses algorithms and flowcharts. It defines an algorithm as an unambiguous set of executable steps to solve a problem. The key control structures for algorithms are sequence, selection, and repetition. It provides examples of algorithms using pseudocode and flowcharts to read grades, calculate averages, and determine if a grade passes or fails.

1. 2ALGORITMS
&
1 1 FLOWCHARTS

2. 2
ALGORITHMS
 Algorithm: Is an ordered set of unambiguous,
executable steps defining a terminating
process
 Unambiguous:during the execution of an
algorithm, the information in the state of the
process must be sufficient to determine
uniquely and completely the action required
by each step

3. ALGORITHMS
Or
 The execution of each step in an
algorithm does not require creative
skills. Rather, it requires only the ability
to follow directions.
3

4. 4
Control Structures
 The key to clear algorithm design lies in
limiting the control structure to only
three structures:
Sequence, Selection, & Repetition
 The following are the basic C and C++
control structures illustrated in flowchart
and statement form:

5. 5
1) Sequence :
Example:
C=A+B

6. 6
2) Selection: if & if/else
if/else Structure(Double
Selection)
T
F
if Structure (Single
Selection)
F T

7. 7
2) Selection: switch
Break
Break
T
F
T
F
Switch Structure(Multiple Selection)

8. 3) Repetition: while & do/while
T
8
F T
while Structure
F
do/while structure

9. 9
3) Repetition: for loop
T
F
for Structure

10. 10
Pseudocode:
 There are several ways to represent
algorithms. Such as pseudocode,
flowcharts, …
 Pseudocode: Individual operations
are described briefly and precisely in
English standard statements consists
of nouns and verbs

11. Pseudocode:
For example, to evaluate the formula for
converting temperature reading from Celsius
to Fahrenheit:
11
F= (9 /5) C + 32
Solution: Algorithm in pseudocode:
Get the value of C
Calculate F
Print F

12. While the flowchart used is shown bellow
(the used control structure is Sequence ):
12
Start
Read C
F=(9/5)C+32
Print F
End

13. Example 1 : Write an algorithm and draw a flowchart to
read the grades of five students , find the average of
these grades and print it
13
Algorithm:
Initialize counter to 1
Initialize total to zero
Initialize average to zero
While counter is less than or equal 5
Input the grade
Add grade into total
average=total/5
Print average
Counter=1
total=0,average=0
If
Counter<5
Read Grade Total=Total+grade
Average=Total/5
End
START
T
F
Print Average
Counter=Counter+1

14. Example2: A student took final exams of 10 courses.
Write an algorithm and draw a flowchart to read the
grades and find their sum and print it.
14
Algorithm:
Initialize Count to 1
Initialize Total to Zero
For Count=1 to 10
Read a Grade
Add Grade to Total
Print Total
START
Count=1
Total=0
If
Count<10
Read Grade Print Total
Total=Total+Grade
END
Count=Count+1
T
F

15. Example 3 : Write an algorithm and draw a flowchart to
read a grade, test it if PASS(more than or equal 50) or
FAIL, and print the result .
15
Algorithm :
Read a Grade
If Grade more than or equal 50
Print PASS
Else Print FAIL
START
Read Grade
If
F T
Grade>50
Print”FAIL” Print”PASS”
END