1) The document discusses software metrics and Halstead's software science measures including program length, vocabulary, volume, difficulty, and effort. It provides the formulas to calculate these measures and an example calculation for a C function. 2) Guidelines are provided for identifying operands and operators when applying Halstead's measures to source code. Various program elements like variables, functions, and statements are classified. 3) The document also discusses other software metrics like lines of code (LOC) and function points which can be used to measure size and complexity. It provides a sample calculation of LOC and function points for a simple program.

1. Software Engineering (KCS-601)
Unit-3 (Second Part): Software Metrics
Dr. Radhey Shyam
Professor
Department of Computer Science and Engineering
SRMCEM Lucknow
(Affiliated to Dr. A.P.J. Abdul Kalam Technical University, Lucknow)
Unit-3 (Second part) have been compiled/prepared by Dr. Radhey Shyam, with grateful acknowledgment
who made their course contents freely available or (Contributed directly or indirectly). Feel free to use this
study material for your own academic purposes. For any query, the communication can be made through
this mail shyam0058@gmail.com.
April 18, 2022

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Course Name: M. Tech Halto AAsae sei C
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Semester: 2nd Logk N, t N
Paper Name: Object Oriented Software Engineering (MTCS-203B) 7
Topic: Halstead's Software Science. ocahulay7,f n
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Halstead's SoftwareScience
Halstead's Software Science
Halstead's complexity measurement was developed to measure a program module's complexiny
directly from source code, with emphasis on
computational complexity.
The Halstead's measures are based on four scalar number derived directly from a program s
source code:
n 1S number of distinct operators.
n2 is number of distinct operands.
eurYante v
Ni is total number of/distinct operators.
N is total number ofdistinct operands
From these numbers, five measures are derived:
Measure Symbol Formula
Program length N N=NI +Na
Programvocabulary N n=nitn2
Volume V=N* (log2 n)
Difficulty D D (n1/2)*(N2/2)
Effort E E=D*V

4. iaistead's uses certain measures such as program length, program vocabulary, v
difficulty, and effort for the given algorithm. By this Halstead's is trying to show that une
program length can be caleulated, volume of algorithm can be estimated. The above given table
shows how actually these measure can be obtained.
The Halstead's measures are applicable to operational system and to development eforts once
the code has been written. Thus using Halstead's measurement experimental verification can be
performed in software science.
Program length:
The length of a program is total usage of operators and operands in the program.
Length (N) =Ni+N2
Program vocabulary:
The Program vocabulary is the number of unique operators and operands used in the program.
Vocabulary (n) = ni t n2
Program Volume:
The Program Volume can be defined as minimum number of bits needed to encode the program.
Volume (V) = N loga n
Length estimation:
N=ni log2 ni t n2 log2 n2
Guideline for caleulating operands and operators:
1. All the variables and constants are considered as operands.
2. Local variables with same name, if occurring in different functions are counted as unique
operand.
3. Function calls are considered as operators.

5. 4 The looping statements, do... while, while, for, are operators. The statements i, i
else, are operators. The switch . . .
case statements are considered as operators.
5. The reserve worlds, returns, default, continue, break, sizeof are all operators.
6. The brackets, commas, semicolons, are operators.
7. The unary and binary operators are considered as operators. The & is considered
as
operator.
8. In arrays, array name and index are considered as operands and [ ] is considered
as
operator.
9. All hash directives can be ignored.
10. Comments are not considered.
11. In Goto statement, goto is considered as operatorand label as operand.
Example: Obtain Halstead's length and volume measure for following C function.
)
(CtinatashengtE
Void swap (int a[ ], int i)
uelwme N n
int temp;
Fr Comptalia H a l s a r e l ' s
m e
bistineF eporators ) {Fi
ne efperards; K 2 3
= -N=)
Temp ali
ail ali+1];:
afi+1]=temp; legti N) =
N,tNa=lct
17
pLabulayln)= n,#n2 = 8t4=12
N=10
We first find out the operands and operators from above function along with their occurrences.
Operands Occurrences Operators Occurrences
swap
5
void
temp
int 3

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=
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N=37
n =nitn2
=
5 +9 =
14
d
-T-
n= 14
Estimated length =
n1 log ni + n2 log n2
=
5 iog 5 +9 log 93 . 1 1
= 5*2.32 +9*2.19 =31.37
GrpeTands eumemeas oralnd |aelunen
Estimated length =
31.37
whde
VolumeN * log n
Y
M
37 *
log (14) d de
381
elu
37*2.63=97.64
3
Volume (V) =
97.64
3
33
13 2
n
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NI =
14.Na 20
Estima longt =
, t73
N=
N+ N,= l4+20 = 3
Rume z
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3(1.58S)+ 13(3-))
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n O S - T T . C

16. References
1. Roger S. Pressman, Software Engineering a Practitioner Approach, 3rd
Edition, TMH, 2005.
2. Rajib Mall, Fundamantal of Software Engineering, 3rd
Edition,PHI Publication, 2007.
3. Deepak Jain, Software Engineering for Practitioners, Ist
Edition, Oxford, 2012.
4. K K Agarwal and Yogesh Singh, Software Engineering, 3rd
Edition,Oxford, 2012.
********************
16