simple file i/o

[corbett]

Saw a thread about a program to add an extra 'b' before 'B' in a file containing 'ABC'. I tried it. Here's my code:

("file1.txt" contains "ABC")

#include<iostream>
#include<fstream>
using namespace std;
int main()
{
ifstream in;
ofstream out;
in.open("file1.txt");
out.open("file2.txt");
char a;

while (!in.eof())
{
in>>a;

if (a=='B' )
{
out<<"bB";
}

else out<<a;

}
return 0;
}

It works except an extra C appears at the end.

O/P in the file:

"AbBCC"

[MiiNiPaa]

while (!in.eof())
DO not use eof() for loop conditions ever. It stops too late.
In your case use

while (in>>a) {
    if(a == 'B') {
//... 

EDIT: Do not forger to replace file1 with file2 to make it like original thread OP wanted.

[corbett]

Thanks! I'll keep that in mind.

[corbett]

What is the syntax to replace the files?

[MiiNiPaa]

It is OS specific, so you should look into your OS headers.
Or you can use boost::filesystem lib to handle files. (Of course you should have boost installed)

for windows: include windows.h and use http://msdn.microsoft.com/en-us/library/windows/desktop/aa363851%28v=vs.85%29.aspx