How to Compare Two Strings in Python?
Looking to validate user input or sort data in Python?
Do not worry! To do so effectively, you are required to compare two strings in Python. But before proceeding further, what is a string in Python?
A String in Python refers to a sequence of characters in single quotes (‘), double quotes (“), or triple quotes (‘’’). It comprises a set of letters, numbers, or symbols. However, string comparison is one of the most widely used operations in programming.
Now, let’s go through the detailed guide to compare two strings in Python!
Why Do You Require to Compare Two Strings in Python?
Comparing strings in Python is crucial for several reasons, such as data manipulation, validation or organizing the text. Some of the common reasons are!
Sorting & Organizing
When arranging a list of strings alphabetically or depending on certain criteria, comparison operators play a vital role in determining proper order.
Data Validation
String comparisons are used to compare two conditional statements like if-else and switch statements. Using the string comparison, you can have the complete program flow and execute the code based on varied conditions.
Equality Check
At times, you are required to check whether two strings showcase a similar text. Such an equality operator helps in checking whether the string values are equal or not.
Searching & Matching
String comparison is specially used to identify the specific substring within the larger strings. In addition to that, it even facilitates determining the matching pattern.
How to Compare Two Strings in Python?
Strings in Python consist of Unicode characters found in the sequence. A string comparison involves evaluating a string sequence to compare for equality, ordering, and similarity. Python provides several operators and methods to make string comparison easier.
Method 1: Using Operators
String comparison can be done with the help of Python comparison operators.
| “==” | Equal to |
| “!=” | Not equal to |
| “<” | Less than |
| “>” | Greater than |
| “<=” | Less than or equal to |
| “>=” | Greater than or equal to |
As a result, such a Python operator is used to compare every character in the string from left to right and provide a result that is either true or false.
Let’s take an example:
string1 = "apple" string2 = "Apple" print(string1 == string2) print(string1 != string2) print(string1 < string2) print(string1 > string2) print(string1 <= string2) print(string1 >= string2)
Output:
False True False True False True
Method 2: User-defined Function
In this method, the comparison of strings takes place on the basis of unicode values. Moreover, if you require to compare strings, it can be done depending on certain criteria. Let’s look at it!
def string_comparison(string1, string2):
count1 = 0
count2 = 0
for j in range(len(string1)):
if string1[j] >= "0" and string1[j] <= "9":
count1 += 1
for j in range(len(string2)):
if string2[j] >= "0" and string2[j] <= "9":
count2 += 1
return count1 == count2
print(string_comparison("hello", "world"))
print(string_comparison("apple", "1234"))
print(string_comparison("hello123", "world456"))
Output:
True False True
Method 3: Using str Method
Python string comparison can be done by startswith() and endswith() methods. Few examples are as follows:
str = 'Hello World'
print(string.startswith('Hello'))
Output:
True
Final Thoughts
String comparison is a powerful feature of Python, which is helpful in many programming situations. Knowing when to use the right methods, whether equal comparisons, case insensitive comparisons, or regex-based methods will make sure that your applications will execute string comparisons correctly and efficiently.
Frequently Asked Questions
How do I check if two strings are equal in Python?
Use the equality operator ==, to check if two strings are equal in Python. The equality operator tests whether two strings have the same sequence of characters.
string1 = “hello”
string2 = “hello”
print(string1 == string2)
Output: True
How can I compare strings in Python ignoring cases?
To compare strings in Python without considering cases, convert both strings to the same case using .lower(), .upper(), or .casefold().
string1 = “Hello”
string2 = “hello”
print(string1.lower() == string2.lower())
Output: True
What is the best way to compare strings in Python?
Comparing two strings in Python depends on your use case:
Use == for a simple equality check that is case-sensitive.
Use .lower() or .casefold() for a case-insensitive equality check.
Use in to see if a string contains another string.
Use locale.strcoll() or unicodedata.normalize() when you care about locale or Unicode-sensitive comparisons.
How do you compare two strings in Python to see if they are not equal?
You can use the != operator to determine if they are not equal:
a = “Python”
b = “Java”
print(a != b)
Output: True
What is the difference between lower() and casefold() in Python?
.lower() will change characters to be all lowercase, but .casefold() is more aggressive and done for the sake of comparing international text (the German character “ß” becomes “ss”). Always use .casefold() when comparing strings, and you need case-insensitive behavior in Python.
Can I compare strings alphabetically in Python?
Yes, Python allows strings to be compared lexicographically with operators < , > , <= , and >=:
print(“apple” < “banana”)
Output: True
How can I compare more than one string at a time in Python?
You can use logical operators for comparing several strings:
a = “Python”
b = “python”
c = “PYTHON”
if a.lower() == b.lower() == c.lower():
print(“All strings are equal (case-insensitive).”)
How to check if one string contains another string in Python?
It is case-sensitive by default, so you will need to use .lower() for case-insensitive checks.
“Python” in “I love Python programming”
Output: True
