I have some code to cout the line from file. and to use it to find word in the file.

[
ifstream bfile("test1.txt");

for(int i=0;i<=4;i++)
{bfile>> word[i];}

for(int i=0;i<=4;i++)
{line = line+ " " + word[i]; }
cout<< line<<endl;
]
after that use find word in string to find or edit in the the line, then take back to the file.

Any other idea to easy understand. I read some other thread, and their idea quite confuse i can't understand.

Read my answer to another your thread on the same topic:
http://www.daniweb.com/forums/thread190507.html
Are you sure that the more threads the better chance to get right answer?