<\/span><\/h2>\n\n\n\nA ternary operator in Python is a one line statement that allows you to evaluate a condition and assign value depending on whether the condition is true or false. It offers a shorter way to write an if-else statement. Here is an example of an if-else statement.<\/p>\n\n\n\n
a = 10
if(a>5){
print('a>5')
}else{
print('a<=5')
}<\/pre>\n\n\n\nIn the above code, we basically check if the value of variable a is greater than 5 or not, and accordingly display an output message.<\/p>\n\n\n\n
Even though our if-else condition is simple, the above code is verbose. You can easily shorten it using ternary operator. Here is its syntax.<\/p>\n\n\n\n
true_value if condition else false_value<\/pre>\n\n\n\nIn the above statement, the condition will be first evaluated. If it is true, then true_value will be evaluated and returned, and false_value is ignored. Else false_value will be evaluated and returned, and true_value is ignored.<\/p>\n\n\n\n
It is faster than conventional if else because when condition is true, only true_value is evaluated and false_value is not evaluated at all. On the other hand, when condition is false, false_value is evaluated and true_value is not evaluated at all. Here are a couple of examples to demonstrate its use.<\/p>\n\n\n\n
>>> 'true' if True else 'false'
'true'
>>> 'true' if False else 'false'
'false'<\/pre>\n\n\n\nThere are some important points to keep in mind while using ternary operators.<\/p>\n\n\n\n
1. The true_value and false_value need to be expressions and not statements. So you cannot use commands like pass, or assignments or even augmented assignments such as += in them. In all these cases, it will throw an error. Here are some examples to illustrate it. Even using parentheses around statements do not work.<\/p>\n\n\n\n
>>> pass if true else pass
File \"<stdin>\", line 1
pass if true else pass
^
SyntaxError: invalid syntax
>>> a=1 if true else a=2
File \"<stdin>\", line 1
SyntaxError: can't assign to conditional expression
>>> (a=1) if true else (a=2)
File \"<stdin>\", line 1
(a=1) if true else (a=2)
^
SyntaxError: invalid syntax<\/pre>\n\n\n\nSince Python 3.8+, you can also use walrus operator ‘:=’ to make simple assignments as expressions. But it can make the code very complicated. So use it only if you have to.<\/p>\n\n\n\n
2. In a typical if-else statement, the else part is optional. But in case of ternary operator, the else part is mandatory. If you do not include it, you will get an error message as shown below.<\/p>\n\n\n\n
>>> a=1
>>> a if True
File \"<stdin>\", line 1
a if True<\/pre>\n\n\n\n3. Another point to keep in mind is that you can use ternary operator to assign variable values. Here is an example.<\/p>\n\n\n\n
>>> a=1
>>> b=2
>>> x=a if True else b
>>> print(x)
1<\/pre>\n\n\n\nIn the above code, the result of ternary operator is assigned to variable x.<\/p>\n\n\n\n
4. Since you can use it for variable assignment, you can also use ternary operator to return values from functions, as shown below.<\/p>\n\n\n\n
>>> x=1
>>> y=2
>>> def check(x,y):
... return x if x>y else x
...
>>> check(a,b)
2<\/pre>\n\n\n\nNow let us look at some other ways to use ternary operators in Python.<\/p>\n\n\n\n