Replace a character of a string by it’s index in Python
In this tutorial, we are going to learn about how to replace a character of a string by its index in Python.
For example, we have a string “python” and we have to replace a character which is at an index 2 with “s” which means “t” will be replaced by “s”. so the final output is “pyson”.
Indexing in Python
- The positions of a string’s characters are numbered from 0, on the left, to the length of the string minus 1, on the right.
For example, we have a string “Hi there” so its indexing is
H | i | t | h | e | r | e | |
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
-8 | -7 | -6 | -5 | -4 | -3 | -2 | -1 |
So this is the indexing of string in python
Addition of two or more strings:
We can add two strings by using simply arithmetic + operation.
For example-
Input: “hel”+”lo”
Output: “hello”
We have many methods to replace a character of a string by its index in Python but here only we discuss only two of them
Using for loop and conditional statement to replace a character of a string by it’s index in Python
Let’s start coding
- 1st we have a string s=”hello” and we want to replace the character which is at index 2 means 1st “l” in “hello” and replace this character with the “i” and final output we want is “heilo”.
- Now we have to create a new empty string to store the characters which we will get in below for loop.
- Then we will run a for loop that runs equal to the length of string s len(s) times.
- In that, we have an if statement which will execute only if i equals that particular index x and at that index, we will add a character that we want to replace.
- Else remaining characters we will add into a new string(newStr) one by one with the help of for loop
s="hello" x=2 #we want to replace character which is at index 2 r="i" #This is character which we want to place at that index newStr="" for i in range(len(s)): if i==x: newStr=newStr+r else: newStr=newStr+s[i] print(newStr)
Output:
heilo
By using arithmetic operation
So in this method, we basically brake our string in two-part.
- 1st part is all the characters before that index which the user wants to replace the character from that position.
- 2nd part is all the characters after that index
- At last, we will add the character(which the user wants to place at that index) in the middle of that parts
let’s start coding:
- 1st we have a string s=”hello” and we want to replace the character which is at index 2 means 1st “l” in “hello” and replace this character with the “i” and final output we want is “heilo”.
- Now we use simple arithmetic addition operation (+) two add those two-part and character which user want to place.
- At last, we will print that new string.
More we understand after seeing the code given below
s="hello" x=2 #we want to replace character which is at index 2 r="i" #This is character which we want to place at that index newStr= s[:x] + r + s[x+1:] print(newStr)
Output:
heilo
let’s understand the above code
s[:x] – It means it will return all the characters from index zero to (x-1)
s[X+1:]- It means it will return all the characters from the index (x+1) to the end.
so we will fetch all the characters except the character at index x from string s and At index x, we have added r which is the character which user wants to replace
Thus, we have learned how to replace a character of a string by its index in Python.
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