Python Data Types: Numeric Types and Strings

Numeric Types and Strings at a Glance

Choose a data type that matches the job: numbers support calculations, while strings represent text such as hostnames, interfaces, addresses, and messages.

1. Python Data Types

A data type tells Python what a value represents and which operations are allowed. A number can be used in a calculation. Text can be joined. A collection can hold several related values.

2. Python Numeric Types

Python has three built-in numeric types. Network scripts mainly use integers and floats. Complex numbers are uncommon in daily network work. Use type() to check a value.

>>> type(-5)
<class 'int'>
>>> 5 - 2
3

>>> type(2.0)
<class 'float'>
>>> 5.0 / 1.3
3.846153846153846
>>> 9 / 2
4.5

>>> type(3.14j)
<class 'complex'>
>>> z = 3 + 4j
>>> type(z)
<class 'complex'>

3. Numeric Conversion

Data from a file, prompt, or API may arrive as text. Conversion functions create a number when a calculation is required. Converting a float with int() removes the decimal part; it does not round the value.

>>> my_float = 1.9
>>> my_int = int(my_float)
>>> print(my_int)
1
>>> float(5)
5.0
>>> int("5")
5
>>> float("3.2")
3.2

Real-world example: count failed checks

total_checks = "24"
passed_checks = "21"
failed_checks = int(total_checks) - int(passed_checks)

print(failed_checks)

The output is 3. Without int(), both values remain text and cannot be subtracted.

4. Python Strings

A string is text. Network scripts use strings for hostnames, interface names, IP addresses, configuration lines, and command output. Create a string with matching single or double quotes.

>>> "hello world"
'hello world'
>>> 'hello world'
'hello world'
>>> "This is my router's output"
"This is my router's output"
>>> 'My router is the "best" there is'
'My router is the "best" there is'

A backslash lets a quote appear inside matching quotes. Triple quotes are useful for text that spans several lines.

>>> print('My router is the \'best\' there is')
My router is the 'best' there is

>>> print("""This is the output of R1:
... Interface GigabitEthernet0/1
... IP address 192.168.1.1 255.255.255.0""")
This is the output of R1:
Interface GigabitEthernet0/1
IP address 192.168.1.1 255.255.255.0

5. String Operations

Use + to join strings and * to repeat them. Both values joined with + must be strings.

>>> "Router " + "R1"
'Router R1'
>>> "Error " * 4
'Error Error Error Error '
>>> "Error Code: " + str(3)
'Error Code: 3'

6. String Formatting

F-strings are the clearest way to place values inside a message. Start the string with f and put each variable or expression inside braces.

>>> hostname = "SW1"
>>> vendor = "Cisco"
>>> platform = "Catalyst"
>>> print(f"Switch {hostname} from {vendor} is a {platform} switch.")
Switch SW1 from Cisco is a Catalyst switch.

>>> uptime = 28800
>>> print(f"Router has an uptime of {uptime / 3600} hours.")
Router has an uptime of 8.0 hours.

An f-string can calculate a value before displaying it. Keep the expression short so the message remains easy to understand.

Real-world example: maintenance result

device = "SW1"
changed_ports = 4
failed_ports = 1

print(f"{device}: {changed_ports - failed_ports} ports passed, {failed_ports} failed")

The output is SW1: 3 ports passed, 1 failed. It includes the device and both results in one line.

7. Conclusion

• Python numeric values include integers, floats, and complex numbers.
• int(), float(), and related functions convert compatible values.
• Strings use single, double, or triple quotes and can contain escaped characters.
• Concatenation joins strings, while str() converts other values for text output.
• F-strings keep formatted output concise and readable.