---

Types and casting in Python

Typecasting allows Python programmers to convert an entity from one data type to another. For instance, you may want to convert a string data type such as “2000” to a number type. But why do you need type casting in Python?”

You may want to take advantage of certain properties of a particular object data type. For instance, you may declare a string variable data type that has the operations of “+ and *) as we have learned earlier in our previous section on strings. But you may want to apply number operations such as “/, - and |.” For you achieve numerical operations on such a data type, you have to convert it, or typecast such a variable, to a number.

To cast between the different data types, you must specify the data type name as the function. There are several built-in functions that can help you to convert from one data type to another. Examples of these functions are: 

Syntax	Description
int(x [base])	It converts the value x to an integer where the base defined is a string or not
long(x [base] )	It converts the value x to the long integer where the base specified is x a string or not
float(x)	It converts the value xto floating point number
complex (real [imag])	It produces a complex number
str(x)	It converts the object x to string data type
eval(str)	It evaluates the string and returns the object
tuple(x)	It converts the value xto a tuple
list(x)	It converts the value x to a list
set(x)	It converts the value xto a set
dict(x)	It converts the value x to a dictionary where x must be a sequence of the (key, value) tuples
chr(x)	It converts the integer to a character
unichr(x)	It converts an integer to the Unicode character
ord(x)	It converts the single character to its integer value
hex(x)	It converts an integer to a hexadecimal string
oct(x)	It converts an integer to an octal string

Have a look at the example of the code below. What do you think will be the output?

x = "5000"
y = "2000"
print(x + y)
print( int(x) + int(y) )

Output

50002000
7000

Can you explain why the output is like that? Well, the first statement (print x+y) will display a concatenation of two strings: 5000 and 2000. In the second statement, the x variable has been converted to integer data type. Similarly, the second variable has also been converted to integer data type. Thus, the statement print (x+y) prints the sum of x and y, which is 7000.

---