c++ - Reading and writing in the same text file using a for loop -

is possible both read , write in text file using 1 for loop? want print out symbol . @ 0 pos , after every 8 chars in text. here's code, doesn't work:

#include <iostream> #include <fstream> #include <string> using namespace std; int main() {     fstream file("mnmn.txt", ios::out | ios::in );     string content;     int i;     while(file >> content)     {         (size_t = 0; < content.size(); i+=8)         {             file<<".";             break;         }     }     return 0; } 

ddta in text file is:

abcdefghijklmnop 

i want become:

.abcdefgh.ijklmnop. 

you cannot - data in file not "shift" when write character, gets written over.

a common approach solving follows:

• open temporary file writing. write dot it
• open source file reading. read 8 characters @ time
• every time read 8 characters source file, write them temp file; append dot
• once reading complete, close both files; move temporary file in place of original.