Exercise 22 Flashcards
puts
put string
Prints a string onto the screen. Includes newline character at the end.
Prints a string onto the screen.
Doesn’t include newline character at the end.
””
double quotes.
Tell Ruby to interpret what’s within the characters as Ruby code.
#
octothorpe or pound symbol. Turns lines of code into comments.
{}
format activator. Tells Ruby to interpolate its contents as code
variable
A name that holds a piece of information.
+
plus operator. Used for addition. Can add numbers or combine strings.
-
minus operator. Used for subtraction.
/
slash operator. Used for division.
*
asterik operator.
Used for multiplication. Can multiply numbers or strings. Two asteriks together will find a number’s exponent.
%
percent.
Can be used as a modulus operator. It finds the remainder after division.
*>
less than.
Comparison operator. Checks to see if an item is less than another.
>
greater than. Comparison operator. Checks to see if an item is greater than another.
<=
less than or equal to. Comparison operator. Checks if an item is less than another. Also checksif the item is equal to the other.
=>
greater than or equal to. Comparison operator. Checks if an item is greater than another.Also checks if the item is equal to the other.
=
assignment operator.
Assigns values to a variable.
.
decimal.
Turns numbers into floats. Also used to call methods on variables.
”
single quotes.
Create strings. Won’t do string interpolation.
true
boolean value.
false
boolean value.
%q{}
Creates a string.
Doesn’t interpolate variable names or other Ruby code.
’’’
triple single quotes.
Used for multi-line strings. Doesn’t interpolate variable names or other Ruby code.
gets
get string.
Records string input from the user.
.chomp
A method.
Removes newline character at the end of a string.
open(filename)
A method.
Takes filename as parameter and returns file object.
\n
newline.
Whitespace character, aka an Escape Sequence. Separates paragraphs from each other.
\t
tab. Whitespace character, aka an Escape Sequence. Indents.
\
backward slash.
Escape sequence. Tells Ruby to print a single backslash inside a string.
()
Parentheses.
Can be used to enter parameters.
.to_i
A method.
Converts string to an integer.
.to_f
A method.
Converts fixnum to a float.
ARGV
Argument variable.
Tells Ruby to take variables, unpack them, and assign values given by the user to the variable names assigned to ARGV.
$stdin
standard input.
Used instead of gets when we enter arguments into the command line.
”””
triple double quotes.
Used for multi-line strings. Interpolates code.
read
A method.
Used on file objects. Returns a file’s contents.
.close
A method.
Used on file objects. Closes file.
ARGV.first
Used when entering only one argument into the command line.
.truncate()
A method.
When used on file objects, it truncates existing contents to zero length.
.length
A string method that returns the length of the string.
.exist?
Returns true if a file exists. Returns false if it doesn’t.
w
“Write-Only” mode.
Passed as an extra parameter to open(filename). Automatically truncates existing file to zero length, or creates a new file for writing.
.write
File object method.
Writes a given string into a file.
def
Keyword used to denote a method’s definition.
end
Keyword that denotes the end of a method’s definition.
*args
Creates a list of arguments, used for multiple arguments.
.seek
Looks for a specific place in the file’s contents.
+=
Positive increment.
Adds to existing variable value. (variable += 1 is the same as variable = variable + 1 )
return
Gets data or variables back from the method.
We can use puts before calling a method, and it will actually print out the return value in our script.
