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Spaces and indentation (tabs) are relevant parts of the code
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Instructions in a block of code will have the same indentation
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A block of code contains one or more lines of code inside it. The contained lines will be indented one more level than the container one.
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A colon : opens a new block of code in the following line.
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# at the beginning of a line marks this line as non-executable. For example
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# This is a single line comment
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To create multiple line comments, use three apostrophees in a row
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'''
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This is a
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Multiline comment
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'''
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There's no declaration of variables. When you use a new name in an assign sentence, that becomes a variable of the type of the value assigned to it
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a = 10 creates a variable called a that stores an integer value
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The decimal separator is the point
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a = 3.14 creates a variable called a that stores a decimal (float) value
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To transform a numerical value into a string you cast it using the function str()
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str(10) will create the string value "10"
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To transform a string value into an integer you cast it using the function int()
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int("10") will create the integer value 10
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print(a)
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Prints the content of the variable called a and opens a new line
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print("Helo world")
Hello word and opens a new line |
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print(a,end=",")
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Prints the content of the variable called a and then a comma without opening a new line
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print(name,end=",")
My name, |
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input()
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Reads a string value form the keyboard
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a = input() will store in a variable called a the value entered by the user as a string
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int(input())
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Reads a string value form the keyboard, ant casts it into an integer
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a = int(input()) will store in a variable called a the value entered by the user casted as an integer
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+
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add
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12 + 5 returns 17
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-
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subtract
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12 - 5 returns 7
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*
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product
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12 * 5 returns 60
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/
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decimal division
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12 / 5 returns 2.4
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//
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division (whole numbers)
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12 // 5 returns 2
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%
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remainder of the division
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12 % 5 returns 2
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**
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exponentiation
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12 ** 5 returns 248832
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<
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less than
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12 < 5 evaluates as False
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<=
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less than or equal to
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12 <= 5 evaluates as False
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==
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equal to
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12 == 5 evaluates as False
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>=
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greater than or equal to
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12 >= 5 evaluates as True
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>
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greater than
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12 > 5 evaluates as True
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!=
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not equal to
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12 != 5 evaluates as True
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<expr1> and <expr2>
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True if and only if the two expressions are True
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(a>0) and (a<5)
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<expr1> or <expr2>
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True if and only if at least one of the two expressions is True
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(a<0) or (a>=5)
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not <expr>
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True if and only if <expression> is False
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not (a==0)
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len
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Calculates the number of elements in the list.
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while (position < len(myList)):
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update
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Modifies the content of a position of the list.
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myList[position] = newValue
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append
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Add a new position at the end of the list, and stores there a value.
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myList.append(newValue)
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insert
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Creates a new position in the middle of the list, and stores there a value.
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myList.insert(position, newValue)
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pop
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Retrieves the value stored at a given position, and then, removes the position.
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value = myList.pop(position)
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delete
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Erases a position of the list.
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delete(myList[position])
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remove
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Locates the first occurrence of a value in the list, and then erases its position.
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myList.remove(value)
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in
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Membership operation. Check for the existence of a value in the list.
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if (value in myList):
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index
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Locates the first occurrence of a value in the list, and returns it's position. In case the valoue is not found, it will generate a run-time error.
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position = myList.index(value)
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count
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Counts the number of occurrencies of a value in the list.
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occ = myList.count(value)
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reverse
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Flips all the values in the list, so the first will become the last and viceversa.
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myList.remove()
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abs(arg)
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receives an integer number as an argument and returns the integer absolute value
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abs(-12) returns 12
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math.fabs(arg)
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receives a float as an argument and returns the float absolute value
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math.fabs(-12.34) returns 12.34
math.fabs(-12) returns 12.0 |
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math.floor(arg)
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receives a float as an argument and rounds it down to the nearest integer
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math.floor(2.5) returns 2
math.floor(-3.4) returns -4 |
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math.ceil(arg)
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receives a float as an argument and rounds it up to the nearest integer
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math.ceil(2.5) returns 3
math.ceil(-3.4) returns -3 |
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math.pi
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returns the value of Pi
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math.pi returns 3.141592653589793
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if (<expr>) :
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Forks the execution stream according to the logical value of the expression <expr>
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if (a == b):
<do something> |
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else:
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As part of an if .. else block, starts the block code to be executed if the expresion was False
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else:
<do something esle> |
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elif (<expr2>):
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Compound an else: statement with a new if statement
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elif (a<b):
<and another> |
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while (<expr>):
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Generates a loop that will run as long as the expression <expr> is True
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while (a<10):
<do something> <update a> |
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
