Python String Comparison

Strings are an essential part of any programming language. Python string comparison methods generally compare the character by character. When comparing strings, we must keep in mind that a string can contain both alphabets and numbers.

Python includes a number of string comparison methods that can be used to compare strings. The two most basic are comparing the two strings directly or via the '=' operators.

Python has a few built-in functions for string comparison, to check whether any 2 strings are equal or not. But there is an important concept here, of what exactly constitutes a string, Python lets you define your own string as an immutable array of characters..

Python string comparison can seem like a fairly simple operation, however, if you're new to this programming language or just new to coding in general, trying to pick up the syntax may be a challenge.

The operator == is commonly used for this and compares Unicode values of all elements in the string and returns either boolean true or false. In reality, there are many more ways to do this and seeing an example of this comparison in action will help greatly with understanding how it works.

However, Python also comes with a few handy built-in operators to facilitate this. There are two comparison operators that can be used: the == operator and the != operator. These work just like they do in mathematics, where 3 == 4 evaluates to False and 3 != 4 evaluates too True.

#1 Comparison using "==" and "!="

String comparison is one of the fundamental functions in a programming language.The == and != are commonly used relation operations for string comparison.

These operators compare values of characters in strings and return either a boolean True or False.

Relation operators used for comparing strings include == and !=. These operators compare the Unicode values of all the elements in a string. Python uses Unicode as its internal encoding format, to store strings

a.) Using "!="

string1 = 'hello'
print(id(string1))
string2 = 'hello'
print(id(string2))
string3 = 'hello'
print(id(string3))
print(string1==string2)
print(string2==string3)

b.) Using "!="

string1 = 'hello'
string2 = 'hello'
string3 = 'hello'
print(string1!=string2)
print(string2!=string3)

#2 Comparison using "is" and "is not"

The is and is not operators are quite similar to == and != respectively. However, unlike the relational operators, is and is not compares to the Identity (id) of the objects and returns true if they share the same identity.

While using the is and is not you need to keep in mind that the identity of the object does not remain the same. This is a fact that can be easily understood when working with immutables. When you change the value of objects, then a new memory allocation is happening thus giving it a new identity.

a.) Using "is"

string1 = 'hello'
string2 = 'hello'
string3 = 'hello'
print(s1 is s2)
print(s2 is s3)

b.) Using "is not"

string1 = 'hello'
string2 = 'hello'
string3 = 'hello'
print(s1 is not s2)
print(s2 is not s3)

#3 Comparison using other Operator

The great thing about Python is that it offers a wide variety of comparison operators; this includes the ability to compare strings in lexicographic order.

Note that this comparison uses Unicode ordering and not alphabetical ordering.

In other words, the alphabetical order based on the ASCII value of each string character is ignored.

Strings can be logically compared in either of two ways: a string compares as equal to another string if they have the same sequence of characters; a string is less than another string if it comes after it in the dictionary.

Python provides the comparison operators shown above, including the additional < and > symbols, and also supports the order relation symbols a < b a < b ==> a =< b, which are suggestive of their kind

To do so, we can use both the less than ( < ) and greater than ( > ) operators. These are used in conjunction with the equality operator to check if two values are either equal to or not equal to each other.

In a string comparison, we also have operators to determine whether one string comes before or after the other in lexicographic order. These are , =. As with numerical comparisons, these operators can only be used to compare strings of equal length.

string_one = "America"
string_two = "Uzbekistan"
if string_one > string_two:
	print("America comes after Uzbekistan in the alphabet.")
elif string_one < string_two:
	print("America comes before Uzbekistan in the alphabet.")

Conclusion

Python is a dynamically typed programming language based on a core interpretation language. It uses comparison operators to determine the value for each variable.

These operators also determine the order in which Python reaches elements of data structures and compares objects.

For example, Python operators can compare in alphabetical order, rather than numerical value. This allows it to detect cases where two strings have identical characters but different strings.

This is a powerful feature that other languages do not offer, making Python useful for an array of applications.

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Further Reading

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