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Delwin Thermitus
Cyber Security

Strings In Depth
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Strings in limitations and viewing characters

String Limitation
- Strings have no size
- You can think of them as a series of characters
- The position of a character with in a string is known as an index
o ‘Hello’ H-e-l-l-o
o Index 0-1-2-3-4
Viewing Characters
- To View Characters at a particular index we use bracket notation([ ])
- Inside of that bracket notation we place the index of the string we’d like to see
▪ ‘Hello’ H-e-l-l-o
▪ Index 0-1-2-3-4
▪ S = ‘Hello’
▪ Print (s[0]) # ‘h’
Slicing Strings
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To look at one character of a string we simply provide the index we would like to see
To look at multiple characters we can use the following syntax [start:end]
The starting index is inclusive while the end index is exclusive

‘Hello’
H-E-L-L-O
Index
0-1-2-3-4
S = ‘Hello’
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Print (s[0:2]) # ‘HE’ – Start from 0 stop before 2
Print (s[1:] # ‘ello’ – start from 1, go to end
Print (s[1:-1]) # ‘ELL’ – Start from 1 stop 1 behind end

Len Function
- Len is used on any inerrable type to determinate the length
S = ‘Hello’
Length_s = len(s)
Print(length_s) #5

String Methods
- Methods are functions that are built in to specify types in python
- Source of these methods will be important to us to get familiar with but there are many
more than we will cover here
- String Methods do not have the ability to modify strings value because strings are non mutative


...
upper()
- S = ‘hElLo’
- S_Lower = S
...
upper() # ‘HELLO’

...
endwith(x)
- S = ‘this is so cool’
- Print(s
...
endswith(‘Kaia’))

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#True
#false


...
find(‘is’) #2
Idx_of_x = s
...
replace(substr, new_substr) provide a substr to replace and what to replace it with
...
split(delimiter)
- provide a marker with in the string to break string repeatedly into a list
- s = ‘you are cool’
- list_of_words = s

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