While working with different datatypes, we might come across a time, when we need to test the datatype for its nature. This article gives ways to test a variable against the data type using Python. Let’s discuss certain ways how to check variable is a string.
Check if a variable is a string using isinstance()
This isinstance(x, str) method can be used to test whether any variable is a particular datatype. By giving the second argument as “str”, we can check if the variable we pass is a string or not.
Python3
# initializing stringtest_string = "GFG"# printing original stringprint("The original string : " + str(test_string))# using isinstance()# Check if variable is stringres = isinstance(test_string, str)# print resultprint("Is variable a string ? : " + str(res)) |
Output:
The original string : GFG Is variable a string ? : True
Check if a variable is a string using type()
This task can also be achieved using the type function in which we just need to pass the variable and equate it with a particular type.
Python3
# initializing stringtest_string = "GFG"# printing original stringprint("The original string : " + str(test_string))# using type()# Check if variable is stringres = type(test_string) == str# print resultprint("Is variable a string ? : " + str(res)) |
Output:
The original string : GFG Is variable a string ? : True
Method 3 : using the issubclass() method.
step-by-step approach
Initialize the variable test_string with a string value.
Print the original string using the print() method.
Check if the variable is a string using the issubclass() method with the following parameters: the type() of the variable and the str class.
Assign the result to a variable called res.
Print the result using the print() method.
Python3
# initializing stringtest_string = "GFG"# printing original stringprint("The original string : " + str(test_string))# using issubclass()# Check if variable is stringres = issubclass(type(test_string), str)# print resultprint("Is variable a string ? : " + str(res)) |
The original string : GFG Is variable a string ? : True
The time complexity of both methods is O(1), and the auxiliary space required is also O(1) since we are only creating a single variable res to store the result.
