Python, like most programming languages, has an if statement that provides branching in your code. An example syntax of Python’s if statement:
x = 3
y = 4
if x == y:
print("They are equal")
else:
print("They are not equal")
The else branch is optional:
if x == y:
print("They are equal")
The expression can be anything that evaluates a True or False Example:
if num >= 5:
if str == “What’s up?”:
if this != that:
if SomeVar:
Take note of example 4 above — in Python, anything that does not equate to zero, Null, or an empty object is True. Example:
>>> s = 0
>>> if s:
... print("True")
... # Python returns nothing - statement is false
>>> s = 1
>>> if s:
... print("True")
...
>>> s = " "
>>> if s:
... print("True")
... # Nothing again- statement is false
>>> s = "Hello"
>>> if s:
... print("True")
...
True
Python includes comprehensive range of boolean operators you can use within your expressions:
< is Less than <= is Less than equal > is Greater than >= is Greater than or equal == is Equal != is Not equal is Is a particular object is not Is not a particular object
Boolean operations are also supported for negating and chaining expressions:
or is Either expression can be True
and is Both expressions must be True
not is Negate the preceeding expression
Python also supports multiple branching using the elif statement:
if [exp1 is True]:
# execute if exp1 is True
elif [exp2 is True]:
# execute if exp2 is True
elif [exp3 is True]:
# execute if exp2 is True
Reference:
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