control, sequence, function

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Cards (69)

  • Control Structure is a block of statements that analyzes variables and chooses a direction in which to go based on a given parameters.
  • Three Fundamental Control Structures:
    Sequence Control Structure
    Decision Control Structure
    Loop Control Structure
  • Sequence Control Structure is a line-by-line execution of statements sequentially in the same order in which they appear in the script.
  • Decision Control Structure is a control structure that depends on whether a condition is true or false. This structure may skip the execution of an entire block of statements or even execute one block of statements instead of another.
  • Loop Control Structure is a structure that allows the execution of a block of
    statements multiple times until a specified condition is met.
  • Simple conditions compare values of two expressions.
  • There are six relational operators in Python, shown in the following table:
  • < less than
    <= less than or equal to
    == equal to
    >= greater than or equal to
    > greater than
    ! = not equal to
  • The if statement in Python is used to implement a decision. Which is used in simple decision.
  • A simple decision has a form of: if statement
    if <condition>:
    <statement>
  • If the condition is mutually exclusive, we can simply use a two-way decision.
  • A two-way decision in Python has the form of:
    if <condition>:
    <statements>
    else:
    <statements>
  • A multi-way decision structure in programming is a structure wherein a decision is nested inside another decision.
  • there is another way to write multi-way decisions that preserves the
    semantics of the nested structures but makes it more simple.
  • multi way has a form of called an if-elif-else statement.
    if <condition>:
    <statements>
    elif <condition>:
    <statements>
    elif <condition>:
    <statements>
    . . .
    else:
    <default statements>
  • type of loop control structure:
    Definite Loops
    Indefinite Loops
  • 3 types of decision control structure:
    simple decision
    two-way decision
    multi-way decision
  • Definite Loops
    -It is a type of loop where the number of iterations/repetitions is known before.
    the start of the execution of the body of the loop.
  • Definite Loops
    -It is implemented by using count-controlled loops.
  • Indefinite Loops
    -It is a type of loop where the number of iterations/repetitions is not known before the start of the execution of the body of the loop.
  • Indefinite Loop
    -It is implemented by using condition-controlled loops.
  • In Python, a definite loop has a general form of:
    for <var> in <sequence>:
    <body>
  • definite
    The <body> is any sequence of Python statements.
  • definite
    The <var> is called the loop index. A loop index is a variable that is used to control a loop.
  • The <sequence> consists of a list of values.
    Example: [1, 3, 5, 7, 9, 11], [1, 2, 3, 4, 5, 6],
  • The range function, in general has this form: range(<expr>)
    It will produce a sequence of numbers that starts with 0 and goes up to, but does not include, the value of <expr>.
  • range (start,n)
    This function produces a sequence
    that starts with the value start and
    continues up to, but does not
    include n.
  • range (start, n, step)
    This function is like the
    two-parameter version, except that
    it uses step as the increment
    between numbers.
  • An accumulator pattern is a common programming pattern in which a final answer is built a piece at a time in a loop.
  • The general accumulator pattern is as follows:
    Initialize the accumulator variable
    Loop until final result is reached
    update the value of accumulator variable
  • In Python, an indefinite loop is implemented using a while statement.
  • The while statement has this form:
    while <condition>:
    <body>
  • indefinite
    The <condition> here is a Boolean expression, that is a true or false statement.
  • indefinite
    The <body> is a sequence of one or more statements.
  • The body of the loop executes repeatedly as long as the condition remains true.
    When the condition is false, the loop terminates.
  • The general pattern for an interactive
    loop is as follows:
    set moredata to ”yes”
    while moredata is ”yes”
    get the next data item
    process the item
    ask user if there is moredata
  • String
    -It is a sequence of characters.
  • String
    -It is formed by enclosing some characters in quotation marks. Python also allows strings to be delimited by single quotes (apostrophes).
  • string is immutable.
  • lists and tuples are more general than strings. They can store multiple items or even sequence of different data types in a single variable.