Q.Example 5.3:

num1 = 10
type(num1)
<class 'int'>
num2 = -1210
type(num2)
<class 'int'>
var1 = True
type(var1)
<class 'bool'>
float1 = -1921.9
type(float1)
<class 'float'>
float2 = -9.8*10**2
print(float2, type(float2))
-980.0000000000001 <class 'float'>
var2 = -3+7.2j
print(var2, type(var2))
(-3+7.2j) <class 'complex'>

Variable Type Identification – From Intuition to Precision

You walk into a room. You see a chair, a table, a cup of water, and a person. Without thinking, you know: the chair is for sitting, the cup holds liquid, the person can talk. You didn't need to be told — you identified what each thing is by its nature and what it can do.

Variable type identification is exactly that, but for data in a program. When you see a piece of information, you need to decide: What kind of thing is this? Is it a number? A word? A true/false value? A list of things? That decision — matching a value to its category — is variable type identification.

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The Intuition: Why Types Matter

Imagine you're writing a recipe. You write: "Add 2 eggs and 3 cups of flour." The number 2 and the word "eggs" are different kinds of things. If you tried to multiply "eggs" by "flour", the recipe would break. Similarly, in programming, adding a number to a word doesn't make sense. The computer needs to know the type of each variable so it knows what operations are allowed.

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The Precise Statement

Variable type identification is the process of determining the data type of a variable — the set of values it can hold and the operations that can be performed on it. In most programming languages, this happens in one of two ways:

1. Static typing (e.g., C, Java, C++): The type is declared explicitly when the variable is created. The compiler checks that you never misuse it.
2. Dynamic typing (e.g., Python, JavaScript, Ruby): The type is inferred from the value assigned to the variable. The same variable can hold different types at different times.

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Common Variable Types (in most languages)

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How to Identify a Variable's Type

In Python, you use the type() function:

x = 10
print(type(x))        # <class 'int'>

y = 3.14
print(type(y))        # <class 'float'>

name = "Alice"
print(type(name))     # <class 'str'>

is_student = True
print(type(is_student))  # <class 'bool'>

In C or Java, the type is written explicitly: