C++ program to replace all the occurrences of a specific word in a text file

By Rati Gupta

This C++ program counts all the occurrences of a specific word in a text file and finds their positions. Then, replaces all of them with another word.

Example

file.txt:- A thesis statement identifies the topic being discussed.

Input:-
Enter your file name: file.txt
Enter the word you want to replace: the
Enter the new word to replace the old one: your

Output:-
Word is found at : 30
Total count: 1 time(s)

Modified file:-
file.txt:- A thesis statement identifies your topic being discussed.

This program uses the case-sensitive approach to find the word.

Approach:

1. Open the file given by the user.

2. Create a file stream variable to store the content of the file.

3. Extract the content from the file stream into a string variable.

4. Find the starting position of the word using the find() function.

5. Replace the word with another word using replace() function.

6. Repeat steps 4 and 5 via the while loop till the end has reached.

7. Write the modified string to the file.

 

#include
#include
#include
#include
using namespace std;

int main()
{
int i=0,cpos;
string new_word,filename,str,old;
stringstream text;                                                  //Creating a string stream to store the data of a file
fstream file_ob;                                                   //creating an input/output stream
 
cout<<"Enter your file name:";
cin>>filename;
cout<<endl<<"Enter the word you want to replace: ";
cin>>old;
cout<<"Enter the new word to replace old one: ";
cin>>new_word;
cout<<"Word is found at: ";

file_ob.open(filename.c_str(), ios::in|ios::out|ios::binary);       //opening a file
text<<file_ob.rdbuf();                                              //now  the content of file is present in text.str()
str=text.str();      
size_t pos = str.find(old);                   //finding first occurence of substring 

while( pos != std::string::npos)             // Repeat till the end is reached
{
 if(pos==0)
 cpos=pos+old.size();
 else
 cpos=pos-1;

 if((isspace(str[cpos])||ispunct(str[cpos])) && (isspace(str[pos+old.size()]))||ispunct(str[pos+old.size()])          //Checking whether found substring is a word or not
 {
  cout<<pos<<" ";
  str.replace(pos,old.length(),new_word);
  i++;
 }
   pos=str.find(old, pos + old.size()+1);     // Get the next occurrence from the current position
}
if(i==0)
cout<<"No position";
cout<<"."<<endl;
cout<<"Total count:"<<i<<" time(s)"<<endl;
if(i>0)
cout<<" *********Your file has been modified**********";
ofstream write_file(filename.c_str(), ios::binary);
write_file <<str; 
file_ob.clear();
file_ob.close();
return 0;
}

Output:-