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Chemistry LibreTexts

9.1: Programming Operators

  • Page ID
    183935
  • Program Operators

    Note, tables for Arithmetic, Comparison, Boolean and Assignment are based on and modified from  https://www.programiz.com/python-programming/operators .

    Arithmetic

    Operator Meaning Example
    + Adds two operands  x + y
    - Subtracts right operand from the left x - y
    * Multiplies two operands x * y
    / Divide left operand by the right one (always results in floating number) x / y
    % Modulus - remainder of the division of left operand by the right x % y (remainder of x/y)
    // Floor division - if positive number, returns the quotient.  If a negative number, returns value rounded down (more negative) x // y
    ** Exponent - left operand raised to the power of right x**y (x to the power y)

     

    Comparison

    These can be used as logic statements in a program, that is, they result in a True of False value that can be used in a logic statement

     

    Operator Meaning Example
    > Greater that - True if left operand is greater than the right x > y
    < Less that - True if left operand is less than the right x < y
    == Equal to - True if both operands are equal x == y
    != Not equal to - True if operands are not equal x != y
    >= Greater than or equal to - True if left operand is greater than or equal to the right x >= y
    <= Less than or equal to - True if left operand is less than or equal to the right x <= y

     

    Boolean

    Like the comparison operator, these are also logic operators and can result in a true or false value

     

    Operator Meaning Example
    and True if both the operands are true x and y
    or True if either of the operands is true x or y
    not True if operand is false (complements the operand) not x

     

    Assignment

    When assigning a variable a value, you can also mathematically operate on the current value of the variable.

     

    Operator Example Equivalent to
    = x = 5 x = 5
    += x += 5 x = x + 5
    -= x -= 5 x = x - 5
    *= x *= 5 x = x * 5
    /= x /= 5 x = x / 5
    %= x %= 5 x = x % 5
    //= x //= 5 x = x // 5
    **= x **= 5 x = x ** 5
    &= x &= 5 x = x & 5
    |= x |= 5 x = x | 5
    ^= x ^= 5 x = x ^ 5
    >>= x >>= 5 x = x >> 5
    <<= x <<= 5 x = x << 5

     

     

    Programming Logic Statements

    These are use case examples of logic statements using program operators.

     

     

    Code Example \(\PageIndex{1}\)

    i % 5 ==4

    Logic

    True if a number divided by 5 has the remainder of 4, ie., 4,9,14....otherwise False.
    Note:

    • if operating on an index number in python, the first index number is 0. So for the values of 0,1,2,3, this would be false, and on the fifth index number (4) would be true. Then values of 5,6,7,8 would be false, with 9 being true, so every 5th value is true.
    • if operating on an index number in R, the first index number is 1, and so the above code would give values of 1,2,3 this would be false with the fourth index being true. Then values of 5,6,7,8 would be false, with 9 being true, so every 5th value is true.  The following code would work in R
      • i % 5 == 0 (stops at i=5,10,15,...)
      •  (i-1) % 5 == 4 (stops at i-1 = 4, 9, 14, ... that is, i=5,10,15,...)