strings, files and arrays
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mystring = “Hello” how can i save the length of the string in the variable x
x = len(mystring)
methods
-methods work similarly to functions. - they are written like this mystring.upper() and return a value
mystring = “Hello” what methods will return 1) “HELLO” 2) “hello”
1) mystring.upper() 2) mystring.lower()
mystring = “Hello” what method will count the number of times “e” occurs in the string
mystring.count(“e”)
mystring = “Hello” what method will replace all instances of “e” with “x” in the string. (output “Hxllo”)
mystring.replace(“e”, “x”)
mystring = “Hello” how can i retreive the first letter of the string
mystring[0]
mystring = “Hello” write a loop which prints each letter of this string seperately.
for i in range (len(mystring)): print(mystring[i])
mystring = “Hello” how can i take a “slice” of this string, leaving only the letters “ell”
mystring[1:3]
mystring = “Hello” how can i take a “slice” of this string, leaving out the first two letters
mystring[2:]
mystring = “Hello” how can i take a “slice” of this string, leaving out the last two letters
mystring[:3]
what does slicing look like in psuedocode
mystring, substring(1,4)
how to reference a file name in your program.
save the name as a string constant. eg. FILENAME = “highscore.txt” then it can be used as myfile
given FILENAME = “highscore.txt” savetext= “200” write some code to save 200 to the text document.
with open( FILENAME, “a”) as myfile: myfile.write(savetext)
given FILENAME = “highscore.txt” write some code to save the contents of the document to a variable x
with open (FILENAME, “r”) as myfile: x= myfile.read()
what are the conditions for reading a text file into a variable
• file must be text only • must be in your python directory
write a list called mylist , that holds the strings “a” “b” “c”
mylist = [“a” , “b”, “c”]
what are items in a list called
elements they can be different data types
make an empty list called mylist. Then append “a” to the list.
mylist = [] mylist.append(“a”)
given mylist =[ “a”, “b”, “c”] write one line of code to print “b” from the list
print(mylist[1])
given mylist =[ “a”, “b”, “c”] write one line of code to ovverwrite the element “b” with “x”
mylist[1] = “x”
mylist =[ “a”, “b”, “c”] delete the element “b” using it’s element number
del mylist[1]
mylist =[ “a”, “b”, “c”] remove the element “b” using it’s content
mylist.remove(“b”)
write a boolean expression that checks if the string “a” is in the list called mylist
“a” in mylist
write an if structure that prints “correct” if the string “b” is found in the list mylist
if “b” in mylist: print(“correct”)