# Python Program to Replace a Particular Word by Another Word from a given String

## Replace a Particular Word with Another Word in Python

Here on this page, we will learn to create a Python Program to Replace a Particular Word with Another Word.

Example :

• Input : s = “Let’s Learn Python from Internet”, s1 = “Internet”, s2 = “PrepInsta”

• Output : “Let’s Learn Python from PrepInsta”

### Method Discussed :

• Method 1: Brute force approach
• Method 2: In-place Replacing

### Method 1

#### Algorithm

• Initialize variable ans which will store empty string, c with -1 value
• Iterate using i till the length of list s
• For each iteration check if i< c. If the condition is true move to the next iteration else move to the else part.
• If the above condition is false Initialize k to zero. Check the condition if s[i] is equal to s1[k] and i+len(s1) is less than or equal to length of s. If true then initialize z to zero.
• Use nested for loop using the j variable from i to length of s +1.  For each iteration initialize z to j.  Check the condition if s[j] is not equal to s1[k]. If true we will come out of this loop else we will increase k by 1.
• If z is equal to i+length(s1)-1 then append s2 at the end of ans variable. Assign c value of i+len(s1). Else append s at the end of ans variable
• Else append s[i] at the end of ans variable
• Return ans variable.

### Python Code

Run
```def modifyString(s, s1, s2):
ans = ""
c = -1
for i in range(len(s)):
if i < c:
continue
k = 0
if s[i] == s1[k] and i + len(s1) <= len(s):
z = 0
for j in range(i, i + len(s1)):
z = j
if s[j] != s1[k]:
break
else:
k += 1

if z == i + len(s1) - 1:
ans += s2
c = i + len(s1)
else:
ans += s[i]
else:
ans += s[i]

return ans

s = "Let's Learn Python from Internet"
s1 = "Internet"
s2 = "PrepInsta"
print("Original String :", s)
print("Modified String :", modifyString(s, s1, s2))```

### Output:

`Original String : Let's Learn Python from InternetModified String : Let's Learn Python from PrepInsta`

### Method 2:

#### In-Built Function

As you know Python is one of the most simple programming languages. Python has an In-Built Functionreplacefor strings. For which we don’t even require any additional libraries. Let’s see how to use it:

Replace Function Format  :-  a.replace(b, c)

• a – Sentence in which you want to replace the word
• b – Word you want to replace from a
• c – Word which is supposed to replace b

### Python Code

Run
```s = "Let's Learn Python from Internet"
s1 = "Internet"
s2 = "PrepInsta"

x = s.replace(s1, s2)

print("Original String :", s)
print("Modified String :", x)```

### Output:

`Original String : Let's Learn Python from InternetModified String : Let's Learn Python from PrepInsta`

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