Programming Knowledge for Software Testers
Tutorial 6: Data Types in Programming

What is Data Type?

Data Type is a classification of the type of data that a Variable or Constant or Method can hold in computer programming.

Data types specify the different sizes and values that can be stored in the variable.

Ex: Character, Number, Number with decimal values, Boolean / Logical data, String, Date, Currency etc…

I am goin to use three different programming langaues to explain this concept:

1) Java
2) Python
3) VBScript

1. Java

i. Java supports explicit declaration of Data Types

ii. Two types of Data Types in Java

a. Primitive Data Types
b. Non Primitive / Reference Data Types

a) Primitive Data Types
1. Integer Data Types - byte, short, int long
2. Relational Data Types - float, double
3. character Data Type - char
4. Conditional Data Type - boolean

Example:

byte a=100;
short b=500;
int c=12345;
long d=98987878787l;

float e=12.34f;
double f=34567.87678;

char g='y';

boolean h=true;

b) Non Primitive / Reference Data Types
String, Array etc...

iii) Data Type Conversion

2) Python

i) Python supports Implicit declaration of Data Types

ii) Python Data Types: Python has the following data types built-in by default, in these categories:

a) Numbers: int, float, complex

b) Text: str

c) Boolean Type: bool

list
tuple,
set
dictionary etc...

Example 1:

a=100
print (a) #100
print (type(a))#int

b=12.34
print (b)#12.34
print (type(b))#float

c=12j
print(c)#12j
print (type(c))#complex

d="India"
print (d)#India
print (type(d))#str

e=True
print(e)#True
print(type(e))#bool

f = ["mango", "apple", "banana"]
g = ("mango", "apple", "banana")
h = {"mango", "apple", "banana"}
print (type(f))#list
print (type(g))#tuple
print (type(h))#set

Example 2:

a=100
print (a) #100
print (type(a))#int

a=12.34
print (a)#12.34
print (type(a))#float

a=12j
print(a)#12j
print (type(a))#complex

a="India"
print (a)#India
print (type(a))#str

3) VBScript

VBScript doesn’t support Explicit declaration of Data Types.

In VBScript only Data type is Variant, It can hold any type of data, based on usage of data VBScript internally considers Data sub types.

Example:

Dim val
val = "India"
MsgBox val ' India

Msgbox (VarType(val)) '8 for String

val = 100
MsgBox val ' 100

Msgbox (VarType(val)) '2 for Integer

val = 12.34
MsgBox val '12.34

Msgbox (VarType(val)) '5 for Double

val = #10/10/2010#
MsgBox val ' 10-10-2010

Msgbox (VarType(val)) '7 for Date

val = True
MsgBox val ' True

Msgbox (VarType(val)) '11 for Boolean

Note: Using VarType Function we can chheck data type....