Compare char in python

Python Compare Two Strings Character by Character

In this article, we are going to how to compare two strings character by character in Python using 3 different ways.

Compare Two Strings Character by Character Using For Loop

Compare Two Strings Character by Character Using While Loop

Compare Two Strings Character by Character Using Zip

Conclusion

1. Compare Two Strings Character by Character Using For Loop

The first way to compare two strings character by character is to use a for loop.

First, check if the length of the two strings are equal. If they are not then return False .

If length is equal then proceed further to compare. If all the characters are equal then return True else return False .

# function to compare two strings character by character def compare_strings(str1, str2): if len(str1) != len(str2): return False else: for i in range(len(str1)): if str1[i] != str2[i]: return False return True str1 = "Hello" str2 = "Hello" print(compare_strings(str1, str2))

2. Compare Two Strings Character by Character Using While Loop

The second way to compare two strings character by character is to use a while loop.

Again we follow the same approach as we did above but this time we use a while loop .

Create a variable i and initialize it to 0 . This will be used to iterate over the strings.

Check if the length of the two strings are equal. If they are not then return False .

If length is equal then proceed further to compare. If all the characters are equal then return True else return False .

# function to compare two strings character by character def compare_strings(str1, str2): i = 0 while i < len(str1): if str1[i] != str2[i]: return False i += 1 return True str1 = "Hello" str2 = "Hello" print(compare_strings(str1, str2))

3. Compare Two Strings Character by Character Using Zip

The third way to compare two strings character by character is to use zip() method.

The zip() method returns a zip object which is an iterator of tuples. Each tuple contains the nth element of each list. The tuple can be unpacked to separate the elements.

For example, if the two strings are "Hello" and "World" , then the zip object will be: [('H', 'W'), ('e', 'o'), ('l', 'r'), ('l', 'd')] .

Let's use this zip object to compare the two strings character by character.

# compare string using zip method def compare_strings(str1, str2): for (x, y) in zip(str1, str2): if x != y: return False return True print(compare_strings("Hello", "World")) # False print(compare_strings("Hello", "Hello")) # True

Conclusion

This is the end of this brief article to compare two strings character by character in Python.

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How To Compare Strings in Python

You can compare strings in Python using the equality ( == ) and comparison ( < , >, != , = ) operators. There are no special methods to compare two strings. In this article, you’ll learn how each of the operators work when comparing strings.

Python string comparison compares the characters in both strings one by one. When different characters are found, then their Unicode code point values are compared. The character with the lower Unicode value is considered to be smaller.

Python Equality and Comparison Operators

Declare the string variable:

The following table shows the results of comparing identical strings ( Apple to Apple ) using different operators.

Operator	Code	Output
Equality	print(fruit1 == 'Apple')	True
Not equal to	print(fruit1 != 'Apple')	False
Less than	print(fruit1 < 'Apple')	False
Greater than	print(fruit1 > 'Apple')	False
Less than or equal to	print(fruit1	True
Greater than or equal to	print(fruit1 >= 'Apple')	True

Both the strings are exactly the same. In other words, they’re equal. The equality operator and the other equal to operators return True .

If you compare strings of different values, then you get the exact opposite output.

If you compare strings that contain the same substring, such as Apple and ApplePie , then the longer string is considered larger.

Comparing User Input to Evaluate Equality Using Operators

This example code takes and compares input from the user. Then the program uses the results of the comparison to print additional information about the alphabetical order of the input strings. In this case, the program assumes that the smaller string comes before the larger string.

fruit1 = input('Enter the name of the first fruit:\n') fruit2 = input('Enter the name of the second fruit:\n') if fruit1  fruit2: print(fruit1 + " comes before " + fruit2 + " in the dictionary.") elif fruit1 > fruit2: print(fruit1 + " comes after " + fruit2 + " in the dictionary.") else: print(fruit1 + " and " + fruit2 + " are the same.") 

Here’s an example of the potential output when you enter different values:

Output
Enter the name of first fruit: Apple Enter the name of second fruit: Banana Apple comes before Banana in the dictionary. 

Here’s an example of the potential output when you enter identical strings:

Output
Enter the name of first fruit: Orange Enter the name of second fruit: Orange Orange and Orange are the same. 

Note: For this example to work, the user needs to enter either only upper case or only lower case for the first letter of both input strings. For example, if the user enters the strings apple and Banana , then the output will be apple comes after Banana in the dictionary , which is incorrect.

This discrepancy occurs because the Unicode code point values of uppercase letters are always smaller than the Unicode code point values of lowercase letters: the value of a is 97 and the value of B is 66. You can test this yourself by using the ord() function to print the Unicode code point value of the characters.

Conclusion

In this article you learned how to compare strings in Python using the equality ( == ) and comparison ( < , >, != , = ) operators. Continue your learning about Python strings.

Thanks for learning with the DigitalOcean Community. Check out our offerings for compute, storage, networking, and managed databases.

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Compare char in python

Last updated: Feb 21, 2023
Reading time · 5 min

# Table of Contents

# Check if all characters in a String are the same in Python

To check if all characters in a string are the same, compare the string to its first character multiplied by the string's length.

If multiplying the first character by the string's length returns True , all characters in the string are the same.

Copied! 
my_str = 'bbb' all_same = my_str == my_str[0] * len(my_str) print(all_same) # 👉️ True if all_same: # 👇️ this runs print('All characters in the string are the same') else: print('NOT all characters in the string are the same') 

We used the equality (==) operator to compare the string to its first character multiplied by the string's length.

Copied! 
my_str = 'bbb' print(my_str[0] * len(my_str)) # 👉️ 'bbb' print('b' * 3) # 👉️ 'bbb' 

We simply create a string of the same length by repeating the first character of the original string.

# Handling the scenario where the string might be empty

If you need to handle a scenario where the string might be empty, use the and boolean operator.

Copied! 
my_str = '' all_same = my_str and my_str == my_str[0] * len(my_str) print(all_same) # 👉️ '' if all_same: print('All characters in the string are the same') else: # 👇️ this runs print('NOT all characters in the string are the same') 

We used the boolean AND operator, so for the if block to run, both conditions have to be met.

This is the most performant approach for checking if a string consists of one character.

Alternatively, you can use the all() function.

# Check if all characters in a String are the same using all()

This is a three-step process:

1. Use a generator expression to iterate over the string.
2. Compare each character to the first character in the string.
3. If the condition is met for all characters, all characters in the string are the same.

Copied! 
my_str = 'bbb' all_same = all(char == my_str[0] for char in my_str) print(all_same) # 👉️ True 

We used a generator expression to iterate over the string.

Generator expressions are used to perform some operation for every element or select a subset of elements that meet a condition.

On each iteration, we compare the current character to the first character in the string and return the result.

The all() built-in function takes an iterable as an argument and returns True if all elements in the iterable are truthy (or the iterable is empty).

If the condition returns False for any of the characters in the string, the all() function short-circuits returning False .

Note that the all() function returns True if the iterable is empty.

Copied! 
my_str = '' all_same = all(char == my_str[0] for char in my_str) print(all_same) # 👉️ True 

# Handling the scenario where the string might be empty

You can check for the string's length if you need to handle this scenario.

Copied! 
my_str = '' all_same = my_str and all(char == my_str[0] for char in my_str) print(all_same) # 👉️ '' if all_same: print('All characters in the string are the same') else: # 👇️ this runs print('NOT all characters in the string are the same') 

The if block runs only if the string is not empty and all characters in the string are the same.

Alternatively, you can use the str.count() method.

# Check if all characters in a String are the same using str.count()

This is a two-step process:

1. Use the str.count() method to count the occurrences of the first character in the string.
2. If the number of occurrences of the first character is equal to the string's length, then all characters in the string are the same.

Copied! 
my_str = 'bbb' all_same = my_str.count(my_str[0]) == len(my_str) print(all_same) # 👉️ True 

The str.count method returns the number of occurrences of a substring in a string.

If the number of occurrences of the first character in the string is equal to the string's length, then the string consists of one character.

You can also use the set() class to achieve the same result.

# Check if all characters in a String are the same using set()

This is a three-step process:

1. Use the set() class to convert the string to a set .
2. Use the len() function to get the length of the set .
3. If the set has a length of 1, then all characters in the string are the same.

Copied! 
my_str = 'bbb' all_same = len(set(my_str)) == 1 print(all_same) # 👉️ True 

We used the set() class to convert the string to a set object.

Copied! 
my_str = 'bbb' print(set(my_str)) # 👉️ 

Set objects are an unordered collection of unique elements, so any duplicate characters get removed when converting to a set .

If the set has a length of 1 , then all characters in the string are the same.

Which approach you pick is a matter of personal preference. I'd use the first approach if prioritizing performance.

On the other hand, I find converting the string to a set to be the most readable.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Check if a character appears twice in a String in Python
• Check if multiple Strings exist in another String in Python
• Check if a String contains an Element from a List in Python
• Check if a String contains a Number in Python
• Check if a String contains only Letters in Python
• Check if a string contains any Uppercase letters in Python
• How to Check if a String contains Vowels in Python
• Check if a string does NOT contain substring in Python
• Check if String ends with a Substring using Regex in Python
• Check if List contains a String case-insensitive in Python
• Check if String starts with any Element from List in Python
• Check if a String starts with a Number or Letter in Python

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