Python Print functions & Strings

Print Function:

The “print()” function in python is used to print on the console window.

Strings:

Python has a built-in string class named ”str”. A string can be enclosed in either single quotes or double quotes.

print('Single Quotes')
print("Double Quotes")

One thing you need to remember that you need to use similar quotes together. And we can also fuss quotes like, double quotes can fuss single quotes and vice verse.

>>>print("Hey.Let's go out.")
Hey.Let's go out.
>>> print('Hey, i am "python"')
Hey, i am "python"

Python strings are “immutable” which means they cannot be changed after they are created (Java strings also use this immutable style). Since strings can’t be changed, we construct new strings as we go to represent computed values. So, for example, the expression (‘hello’ + ‘there’) takes in the 2 strings ‘hello’ and ‘there’ and builds a new string ‘hellothere’.

Characters in a string can be accessed using the standard [ ] syntax, and like Java and C++, Python uses zero-based indexing, so if str is ‘hello’ str[1] is ‘e’. If the index is out of bounds for the string, Python raises an error.

The len(string) function returns the length of the string. The ‘+’ operator can concatenate two strings.

>>> s = "Hello"
>>> print(s[1])
e
>>> print(len(s))
5
>>> print(s + "there")
Hellothere

A “raw” string literal is prefixed by an ‘r’ and passes all the chars through without special treatment of backslashes, so r’x\nx’ evaluates to the length-4 string ‘x\nx’.

>>> raw = r"Hello \t\n Python"
>>> print(raw)
Hello \t\n Python

String Methods:

Here are the most common string methods:

• s.lower(), s.upper() — returns the lowercase or uppercase version of the string
• s.strip() — returns a string with whitespace removed from the start and end
• s.isalpha()/s.isdigit()/s.isspace()… — tests if all the string chars are in the various character classes
• s.startswith(‘other’), s.endswith(‘other’) — tests if the string starts or ends with the given other string
• s.find(‘other’) — searches for the given other string (not a regular expression) within s, and returns the first index where it begins or -1 if not found
• s.replace(‘old’, ‘new’) — returns a string where all occurrences of ‘old’ have been replaced by ‘new’
• s.split(‘delim’) — returns a list of substrings separated by the given delimiter. The delimiter is not a regular expression, it’s just text. ‘aaa,bbb,ccc’.split(‘,’) -> [‘aaa’, ‘bbb’, ‘ccc’]. As a convenient special case s.split() (with no arguments) splits on all whitespace chars.
• s.join(list) — opposite of split(), joins the elements in the given list together using the string as the delimiter. e.g. ‘—‘.join([‘aaa’, ‘bbb’, ‘ccc’]) -> aaa—bbb—ccc

String Slices:

The slice s[start:end] is the elements beginning at start and extending up to but not including end. Let’s take an example s=”Hello”

>>> s="Python"
>>> print(s[:]) #similar to printing whole string
Python
>>> print(s[1:]) #from 1 to end of string
ython
>>> print(s[1:4]) #from 1 to 3rd of string
yth
>>> print(s[1:100]) #from 1 to end of string
ython
>>> print(s[-1]) #last char
n
>>> print(s[-4]) #4th from the end
t
>>> print(s[:-3]) #going up to but not including the last 3 chars.
Pyt
>>> print(s[-3:]) #starting with 3rd to end of string
hon

So, that covers the basic of print and string function.

So be connected. Thanks for visiting.