Addition, subtraction, multiplication, and exponentiation all do what you expect. When a variable name appears in the place of an operand, it is replaced with the value that it refers to before the operation is performed.
For example, what if we wanted to convert minutes into hours. What if, on the other hand, we had wanted to know how many whole hours there are and how many minutes remain. To help answer this question, Python gives us a second flavor of the division operator. Four does not go into three any times so the original three is still left over. The diagram below shows what is happening. Remember, the modulo operator returns the remainder after performing division.
The remainder is three. One common use for the Modulo Operator is to find even or odd numbers. The code below uses the modulo operator to print all odd numbers between 0 and This is sometimes useful, e. Because not has to invent a value anyway, it does not bother to return a value of the same type as its argument, so e.
The expression x if C else y first evaluates the condition, C not x ; if C is true, x is evaluated and its value is returned; otherwise, y is evaluated and its value is returned. See PEP for more details about conditional expressions.
Lambda expressions sometimes called lambda forms have the same syntactic position as expressions. They are a shorthand to create anonymous functions; the expression lambda arguments: expression yields a function object.
The unnamed object behaves like a function object defined with. See section Function definitions for the syntax of parameter lists. Note that functions created with lambda expressions cannot contain statements or annotations. An expression list containing at least one comma yields a tuple. The length of the tuple is the number of expressions in the list.
The expressions are evaluated from left to right. The trailing comma is required only to create a single tuple a. To create an empty tuple, use an empty pair of parentheses:. Python evaluates expressions from left to right. Notice that while evaluating an assignment, the right-hand side is evaluated before the left-hand side.
The following table summarizes the operator precedences in Python, from lowest precedence least binding to highest precedence most binding. Operators in the same box have the same precedence.
Unless the syntax is explicitly given, operators are binary. Operators in the same box group left to right except for comparisons, including tests, which all have the same precedence and chain from left to right — see section Comparisons — and exponentiation, which groups from right to left. The import system. Simple statements. Enter search terms or a module, class or function name. Navigation index modules next previous Python » 3.
For built-in objects, there are two types of objects that support subscription: If the primary is a mapping, the expression list must evaluate to an object whose value is one of the keys of the mapping, and the subscription selects the value in the mapping that corresponds to that key.
Note In the current implementation, the right-hand operand is required to be at most sys. Comparison of objects of the same type depends on the type: Numbers are compared arithmetically. The function math. Which approach is more appropriate depends on the application.
To compare strings in a human recognizable way, compare using unicodedata. Check their documentation for more info. Table Of Contents 6. Expressions 6. Arithmetic conversions 6.
Atoms 6. Identifiers Names 6. Literals 6. Parenthesized forms 6. Displays for lists, sets and dictionaries 6. List displays 6. Set displays 6. Dictionary displays 6. Generator expressions 6. Yield expressions 6. Generator-iterator methods 6. Examples 6. Primaries 6. Attribute references 6. Subscriptions 6. Slicings 6. Calls 6. The power operator 6. Unary arithmetic and bitwise operations 6.
Binary arithmetic operations 6. Shifting operations 6. Binary bitwise operations 6. Comparisons 6. Boolean operations 6. Conditional expressions 6. Lambdas 6. Expression lists 6.
Evaluation order 6. Operator precedence Previous topic 5. The import system Next topic 7. The Python Software Foundation is a non-profit corporation. We use binary format to store values in computers. The output should be 0 because 3. But, the float fraction values are not exactly represented and the approximation is causing this error. So, you should give extra care when working with floating point numbers.
0コメント