Tokens In Python
A token is the smallest individual unit in a python program. Python have following tokens
- 1. Keywords - These are reserved words which have special meaning for the interpreter.
- 2. Identifiers - These are the names given to the different parts of the program.
- 3. Literals - These are tokens which have fixed value.
- 4. Operators - These are symbols which when put between two operands performs some operation.
- 5. Punctuators - These are symbols used to organize statements, or structures in a program.
Keywords
In Python 3.0.7, there are 33 keywords.
| False | await | else | import | pass |
| None | break | except | in | raise |
| True | class | finally | is | return |
| and | continue | for | lambda | try |
| as | def | from | nonlocal | while |
| assert | del | global | not | with |
| async | elif | if | or | yield |
Identifiers
Some rules you need to keep in mind while creating Identifiers.
- The first character should be letter, or +underscore. No numbers should be the first letter.
- It should not be a keyword.
- Identifers are case-sensitve.
- Except _underscore no symbol is allowed.
Some valid Identifers are:
Hello _Crackexams99
Some invalid Identifers are:
8Hello True
Literals
There are different types of literals:
- String literals - Letters enclosed in quotes ''/"" are called string literals.
- Numeric literals - There are generally three types which are int, float, and complex.
- Boolean literals - It is True or False.
- None - It indicates nothing.
Operators
There are different types of operators:
- Unary Operators - Requires only one operand.
- Binary Operators - Requires two operand.
-Arithmetic Operators
| Operator | Function | Syntax |
|---|---|---|
| + | Add two operands or unary plus | x + y |
| - | Subtract right operand from the left or unary minus | x - y |
| * | Multiply two operands | x * y |
| / | Divide left operand by the right one (always results into float) | x / y |
| % | Modulus - remainder of the division of left operand by the right | x % y |
| // | Floor division - division that results into whole number adjusted to the left in the number line | x // y |
| ** | Exponent - left operand raised to the power of right | x**y |
-Bitwise Operators
| Operator | Meaning | Syntax |
|---|---|---|
| & | Bitwise AND | x & y |
| | | Bitwise OR | x | y |
| ~ | Bitwise NOT | ~x |
| ^ | Bitwise XOR | x ^ y |
| >> | Bitwise right shift | x >> 2 |
| << | Bitwise left shift | x << 2 |
-Membership Operators
| Operator | Function | Syntax |
|---|---|---|
| in | True if value/variable is found in the sequence | 5 in x |
| not in | True if value/variable is not found in the sequence | 5 not in x |
-Identity Operators
| Operator | Function | Syntax |
|---|---|---|
| is | True if the operands are identical | x is True |
| is not | True if the operands are not identical | x is not True |
-Logical Operators
| Operator | Function | Syntax |
|---|---|---|
| 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 | not x |
-Relational Operators
| Operator | Function | Syntax |
|---|---|---|
| > | Greater than | x > y |
| < | Less than | x < y |
| == | Equal to | x == y |
| != | Not equal to | x != y |
| >= | Greater than or equal to | x >= y |
| <= | Less than or equal to | x <= y |
-Assignment Operators
| Operator | Use | Syntax |
|---|---|---|
| = | x = 1 | x = 1 |
| += | x += 1 | x = x + 1 |
| -= | x -= 1 | x = x - 1 |
| *= | x *= 1 | x = x * 1 |
| /= | x /= 1 | x = x / 1 |
| %= | x %= 1 | x = x % 1 |
| //= | x //= 1 | x = x // 1 |
| **= | x **= 1 | x = x ** 1 |
| &= | x &= 1 | x = x & 1 |
| |= | x |= 1 | x = x | 1 |
| ^= | x ^= 1 | x = x ^ 1 |
| >>= | x >>= 1 | x = x >> 1 |
| <<= | x <<= 1 | x = x << 1 |
Punctuators
These are symbols used to organize statements, or structures in a program. Examples are ' " \ # @ , : = ( ) [ ] { }