Python Tutorial 4---"String Slicing And Other Functions In Python"
Python Tutorial 4---
"String Slicing And Other Functions In Python"
This PROGRAM or TUTORIAL about Python's "String Slicing And Other Functions In Python"
DOC
String is a data type in Python. Strings in Python programming language are arrays of bytes representing a sequence of characters. In simple terms, Strings are the combination or collection of characters enclosed in quotes.
Primarily, you will find 3 types of strings in Python :
- Single Quote String – (‘Single Quote String’)
- Double Quote String – (“Double Quote String”)
- Triple Quote String – (‘’’ Triple Quote String ‘’’)
Let us now look into some functions you will use to manipulate or perform operations on strings.
len() Function : This len() function returns the total no. of characters in a string. E.g. for string a="abc", len(a) will return 3 as the output as it is a string variable containing 3 characters
Strings are one of the most used data types in any programming language because most of the real-world data such as name, address, or any sequence which contains alphanumeric characters are mostly of type ‘String’.
E.g. Consider this string variable x
This string variable x contains a string containing 11 characters (including spaces). Since the index in a string starts from 0 to length-1, this string can be looked at as:
Note: The indexes of a string begin from 0 to (length-1) in the forward direction and -1,-2,-3,…, -length in the backward direction.
String Slicing :
As we know the meaning of the word ‘slice’ is ‘a part of’. I am sure you have sliced paneer cubes at home!
Just like paneer slice refers to the part of the paneer cube; In Python, the term ‘string slice’ refers to a part of the string, where strings are sliced using a range of indices.
To do string slicing we just need to put the name of the string followed by [n:m]. It means ‘n’ denotes the index from which slicing should start and ‘m’ denotes the index at which slicing should terminate or complete. Let's look into an example!
For E.g. abc="Demo" then abc[0:3] will give ‘Dem’ and will not give ‘Demo’ coz index number of ‘D’ is 0, ‘e’ is 1, ‘m’ is 2, and ‘o’ is 3. So it will give a range from n to m-1 i.e. 0 to 3-1=2. That’s why we got output ‘Dem’.
Let's end this tutorial by looking into some of the most used string functions :
string.endswith(): This function allows the user to check whether a given string ends with passed argument or not. It returns True or False.
string.count(): This function counts the total no. of occurrence of any character in the string. It takes the character whose occurrence you want to find as an argument.
string.capitalize(): This function capitalizes the first character of any string. It doesn’t take any argument.
string.upper(): It returns the copy of the string converted to the uppercase.
string.lower(): It returns the copy of the string converted to lower case.
string.find(): This function finds any given character or word in the entire string. It returns the index of first character from that word.
string.replace(“old_word”, “new_word”): This function replaces the old word or character with a new word or character in the entire string.
CODE
#String Slicing And Other Functions In Python
mystr = "Saswata is a good boy"
print(mystr[0:7]) #Output =Saswata
"""Python's Index starts with 0, Example
Saswata is a good boy - here 0=S, 1=a, 2=s, 3=w, 4=a, 5=t, 6=a, 7= (blank/space)
if we want to print just one alphabet of the string we can use print(mystr[any single number])
but if we want print to print just a word instead of the whole string, we'll use
print(mystr[0:7]), it'll print my name. Output = Saswata
We can't use 6 in here beacuse the last num always excludes in strings
if we use 6 like--- print(mystr[0:6]), Output = saswat"""
#if we want print length of the string, we use len function, example---
print(len(mystr)) #Output=21 [as it starts from 0 so it's 21, if it starts from 1 the output would 20]
print(mystr[0:50]) #Output=Saswata is a good boy
#Yes, we can write big excl num if we want,
# but output will be the same amount of number as put in our variable "mystr"
print(mystr[::]) #Output=Saswata is a good boy
"""print(mystr[::]) here [its always 0:its the length:if its blank its always 1]
example --- [::] and [0:21:1] both are same.
[::2/3/5] if we put more than 1 in the last sec it will skip that times of nums.
It's called 'EXTENDED SLICING' """
print(mystr[-4:-2]) #Output= b
#It's negative index if we want to print our string from backwards, we can use that.
print(mystr[::-1]) #Output=yob doog a si atawsaS
#it'll print backwards,
#if I put -2 instead -1, first it'll print it all backwards then skip the chars.
print(mystr[::-2]) #Output=ybdo iaasS
print(mystr.isalnum()) #Output = False
#it's false because it's not an AlphaNumeric string, i has spaces, if we remove them it'll be true.
print(mystr.isalpha()) #Output = False
print(mystr.endswith("boy")) #Output = True
#it's true because the string does end with 'boy', if I put some other word like 'ball' the it'll be false.
print(mystr.count("a")) #Output=4
#counts function counts the number chars in the strings
print(mystr.capitalize()) #Output = Saswata is a good boy
print(mystr.replace("is", "are")) #Output = Saswata are a good boy
print(mystr.upper()) #Output = SASWATA IS A GOOD BOY
print(mystr.lower()) #Output saswata is a good boy
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