Python Strings
String Literals
String literals in python are surrounded by either single quotation marks, or double quotation marks.
'hello' is the same as "hello".
Strings can be output to screen using the print function. For example: print("hello").
Like many other popular programming languages, strings in Python are arrays of bytes representing unicode characters. However, Python does not have a character data type, a single character is simply a string with a length of 1. Square brackets can be used to access elements of the string.
Example
Get the character at position 1 (remember that the first character has the position 0):
a = "Hello, World!"
print(a[1])
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Example
Substring. Get the characters from position 2 to position 4:
b = "Hello, World!"
print(b[2:4])
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Example
The strip() method removes any whitespace from the beginning or the end:
a = " Hello, World! "
print(a.strip()) # returns "Hello, World!"
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Example
The len() method returns the length of a string:
a = "Hello, World!"
print(len(a))
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Example
The lower() method returns the string in lower case:
a = "Hello, World!"
print(a.lower())
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Example
The upper() method returns the string in upper case:
a = "Hello, World!"
print(a.upper())
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Example
The replace() method replaces a string with another string:
a = "Hello, World!"
print(a.replace("H", "J"))
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Example
The split() method splits the string into substrings if it finds instances of the separator:
a = "Hello, World!"
print(a.split(",")) #
returns ['Hello', ' World!']
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Command-line String Input
Python allows for command line input.
That means we are able to ask the user for input.
The following example asks for the user's name, then, by using the
input() method, the program prints the name to
the screen:
Example
demo_string_input.py
print("Enter your name:")
x = input()
print("Hello, " + x)
Save this file as demo_string_input.py, and load it through the command line:
C:\Users\Your Name>python demo_string_input.py
Our program will prompt the user for a string:
Enter your name:
The user now enters a name:
Linus
Then, the program prints it to screen with a little message:
Hello, Linus
