Section 15.5 Chapter Summary
Chapter 3 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 calledstring3
with all the characters from the first string,string1
, followed by all the characters in the second string,string2
. - Function - A function returns a value. Functions 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”.
Subsection 15.5.1 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 occurrence 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"
.
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