Chapter 4 - Summary¶
Chapter 4 included the following concepts from computing.
Append - You can add two strings together using the
+symbol. This is also called concatenate.Capitalize - The capitalize function returns a new string with the first character capitalized.
Concatenate - You can use
+to concatenate (append) two strings like thisstring3 = string1 + string2. This will create a new string calledstring3with all the characters from the first string,string1, followed by all the characters in the second string,string2.Function - A function returns a value. Function can take input as well, but don’t have to. An example is the string
lower()function that returns a string with all lowercase letters.Immutable - Immutable means that it does not change. Strings are immutable in Python. When you call a function that appears to change a string, it will actually return a new string.
Index - An index is a number associated with the position of a character in a string. In Python the first character in a string is at index 0.
Object - An object can have behavior (things it can do). For example a turtle object can go forward a specified amount. Strings and turtles are objects in Python.
String - A string is a sequence of characters. You specify a string as characters inside a pair of single, double, or triple quotes.
Substring - A substring is a part of a string. One substring of “Hi there” would be “Hi”.
Summary of String Functions¶
Chapter 4 also included the following string functions.
append - You can add two strings together using the
+symbol. This is also called concatenate. The result of"Happy" + " Birthday"is"Happy Birthday".find - The find function takes a string as input and returns the index of the first occurence of that string in the string the function is called on. The code
"goodbye".find('bye')returns 4.len - The len function that can take a string as input and returns the number of characters in the string including any spaces. For example
len("Hi there")will return 8.lower - The lower string function returns a new string with only lowercase letters. For example
"ALL CAPS".lower()returns"all caps".slice - You can get part of a string which is also called a substring using [start] or [start:end] which will return a substring of the current string starting at the given start position and if an end position is given ending at the character before the end position. For example
"out"[1]will return"u"and"otter"[2:5]returns"ter".
Note
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