Search and replace

[Dlazyguy]

How would I be able to search for a number and change it in a text file?
I looked through many sites and this forum and have not yet found something useful.
For example:

file content:

12 dogs bark at the moon at 9
Lets say some bad weather happened so the dog delays its barking by 2 hours.
So now the text file should say

12 dogs bark at the moon at 11

[Duthomhas]

Read the file into memory.

Change the data in memory.

Overwrite the file with the changes.



Reading the file as a collection of strings:

deque <string> data;
string s;
while (getline( f, s )) data.push_back( s );

Reading the file as a single string:

ostringstream ss;
ss << f.rdbuf();
string data = ss.str();

Hope this helps.

[Dlazyguy]

thanks!, I managed to do it some way but I can't figure out why it won't output to texfile but even then how I would I be able to replace the line with the intended output?

if (find(ids.begin(), ids.end(), newid) != ids.end())//Since the original line was stored in a vector i was able to use this to see if the input ID matches the file
{
   fstream edit;//opens file
   edit.open("books.txt");
   if (!edit)
      
    {cout<<"Error opening file"<<endl;
}
   
   cout<<"This book already exists"<<endl;
   unsigned int curLine = 0;
   string line;
   string search;
   cout<<"Enter ID again"<<endl;
   cin>>search;
//Gets line number which corresponds to the vector cell and i was able to update the copies of the books of the line
   while(getline(edit, line)) { // I changed this, see below
    curLine++;
    if (line.find(search) != string::npos) {
        cout << "found: " << search << "line: " << curLine << endl;
        copy[curLine-1]=copy[curLine-1]+1;
        cout<<copy[curLine-1];
        edit.clear();
        edit<<ids[curLine-1]<<titles[curLine-1]<<authors[curLine-1]<<cat[curLine-1]
        <<copy[curLine-1];//This is the troublesome part won't output to texfile no changes were made to the file and I want this to replace the line
    }

[anup30]

int n1, n2;
string str;

get n1;
get str;
get n2;

n2 += 2;

write n1+" " + str + " " + n2;