Swap two strings in python

Swap Characters in a Python String with this Method

In this tutorial, we will look at how to swap two characters in a Python string with the help of some examples.

Can you change characters in a Python string in place?

No. Strings in Python are immutable so you cannot modify a string after it has been created, you can, however, create a new string with the modified value and assign it to the original variable.

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# create a string name = "Tim" # you cannot modify the string name[0] = "J" # this will give an error

--------------------------------------------------------------------------- TypeError Traceback (most recent call last) Cell In[2], line 4 2 name = "Tim" 3 # you cannot modify the string ----> 4 name[0] = "J" # this will give an error TypeError: 'str' object does not support item assignment

Get the memory location of the variable name .

Let’s reassign the value to the variable name with a different value.

# reassign the value to name name = "Jim" # show memory location id(name)

You can see that we cannot modify a string since it’s immutable. You can, however, create a new string and assign it the same variable (notice that the memory location of name after this operation is different from before).

Thus, to swap characters in a string, you’ll have to create a new string with the swapped characters.

How to create a new string with the required characters swapped?

You can use a list to swap characters in a string. Lists in Python are mutable. Use the list() constructor to get a list of individual characters in a string and then swap the characters by their indices using the following syntax –

# create a list from string characters ls = list(s) # swap the values at indices i and j ls[i], ls[j] = ls[j], ls[i] # create a new string with the swapped characters s = "".join(ls)

In the above code, we take the following steps –

1. Create a list from the string characters by using the list() constructor.
2. Swap the required characters in the list using their indices.
3. Join the list values into a new string and assign it to the original string variable (you can assign it to a new variable if you want to keep the original value).

Note that swapping two characters in a string is different from replacing a character with another character (see the detailed example below).

Let’s now look at some use cases of swapping string characters with the help of some examples.

Example – Swap string characters using a list

Let’s say we have a string and we want to swap the characters at the i and j indices.

# create a string s = "batman" # create a list from string ls = list(s) # indices of values to swap i = 0 j = 2 # swap the values ls[i], ls[j] = ls[j], ls[i] # join the list characters into a new string s = "".join(ls) # display the string print(s)

Here, we swap the characters at the indices 0 and 2 in the string “batman”. Note that the resulting string is a new string, “tabman”.

Example – Swap the first and last characters

We can use the above syntax to swap two characters at any index. To swap the first and the last values, use the index 0 (for the first element) and length-1 (for the last element).

# create a string s = "batman" # create a list from string ls = list(s) # indices of values to swap i = 0 j = len(ls)-1 # swap the values ls[i], ls[j] = ls[j], ls[i] # join the list characters into a new string s = "".join(ls) # display the string print(s)

The first and the last characters have been swapped.

How is swapping characters different from replacing characters in a String?

When swapping characters, we’re simply exchanging the position of two characters (both of which are in the string). Replacing a character with another character simply means replacing one (or more) occurrences of a character with a new character whether or not the new character is originally present in the string.

In one of the examples above, we swapped the characters “b” and “t” in the string “batman”. Now, if you want to replace, let’s say “b” with “c” (a character that is not present) in the word “batman”, you can do so using the Python string replace() function, which returns a new string with the replaced characters.

# replace "b" with "c" s = "batman" print(s.replace("b", "c"))

We get “catman” by replacing “b” with “c”.

FAQs

No. Strings are immutable in Python and thus cannot be modified once they are created. You can, however, create a new string with the characters swapped using a list.

You can convert the string to a list of characters, then use the list indexing to swap values in the list at the required indices. You can then convert the list of characters to a string using the string join() function.

No, the replace() method replaces a specific character or substring with another character or substring, this is different from swapping (or exchanging the position) of two characters that are present in the string.

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Author

Piyush is a data professional passionate about using data to understand things better and make informed decisions. He has experience working as a Data Scientist in the consulting domain and holds an engineering degree from IIT Roorkee. His hobbies include watching cricket, reading, and working on side projects. View all posts

Data Science Parichay is an educational website offering easy-to-understand tutorials on topics in Data Science with the help of clear and fun examples.

Источник

How do you swap two strings in python?

How can I swap two strings without using the third string?

How do you swap two string variables without using third or temp variable in java?

How do you swap words in Python?

Join the words using the join function and print it….Algorithm

1. Initialize the string.
2. Split the string on space and store the resultant list in a variable called words.
3. Reverse the list words using reversed function.
4. Convert the result to list.

Is there a swap function in Python?

In Python, you can easily swap values without temp (temporary variable). It is possible to swap values of variables and to swap values (elements) in a list.

How do you swap two variables?

The bitwise XOR operator can be used to swap two variables. The XOR of two numbers x and y returns a number that has all the bits as 1 wherever bits of x and y differ. For example, XOR of 10 (In Binary 1010) and 5 (In Binary 0101) is 1111 and XOR of 7 (0111) and 5 (0101) is (0010).

How do you split a string into two equal parts?

1. STEP 1: START.
2. STEP 2: DEFINE str = “aaaabbbbcccc”
3. STEP 3: DEFINE len.
4. STEP 4: SET n =3.
5. STEP 5: SET temp = 0.
6. STEP 6: chars = len/n.
7. STEP 7: DEFINE String[] equalstr.
8. STEP 8: IF (len\%n!=0) then PRINT (“String can’t be divided into equal parts”) else go to STEP 9.

How do you swap items in a list in Python?

Use multiple assignment to swap the value at each index in the list.

1. a_list = [“a”, “b”, “c”]
2. index1 = a_list. index(“a”)
3. index2 = a_list. index(“c”)
4. a_list[index1], a_list[index2] = a_list[index2], a_list[index1]
5. print(a_list)

How do I swap a list in Python?

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Python Program to Swap Two Strings

This article covers a program in Python, that swaps two strings, entered by user at run-time of the program.

Swap Two Strings in Python

The question is, write a Python program to swap two given strings. The program given below is its answer:

print("Enter the First String: ", end="") string1 = input() print("Enter the Second String: ", end="") string2 = input() print("\nString before swap:") print("string1 blue">print("string2 blue">print("\nString after swap:") print("string1 blue">print("string2 img_box"> 

print("Enter the Two Strings: ", end="") strOne = input() strTwo = input() print("\nString before swap:") print("strOne = \"", strOne, "\"", sep="") print("strTwo = \"", strTwo, "\"", sep="") x = strOne strOne = strTwo strTwo = x print("\nString after swap:") print("strOne = \"", strOne, "\"", sep="") print("strTwo = \"", strTwo, "\"", sep="")