Prints string on console with cout.write() function only after I Quit the application

Question

Inserting an string using cin.getline() and want to print that string on console using cout.write().Prints the entered string after I quit the application

#include<iostream.h>
#include<conio.h>
int main() {
char str[20];
cout<<"Enter a string:";
cin.getline(str,20);
cout<<"Entered string:";
cout.write(str,20);
cout.flush();
getch();
return 0;
}

@πάντα ῥεῖ its working but its also printing '<' after the string. I am using Turbo C++ for practice. — Ayushi Sharma, Mar 02 '19 at 14:46
Take a look at: https://stackoverflow.com/questions/213907/c-stdendl-vs-n — mrflash818, Mar 02 '19 at 14:55
@AyushiSharma I'm explaining the behavior in more depth in the answer I wrote. — πάντα ῥεῖ, Mar 02 '19 at 14:57
@AyushiSharma BTW `` and `` aren't standard c++ headers. You're probably using the turbo-c++ compiler that was already deprecate at the end of the last millenium. Consider to use a more modern compiler to learn c++. — πάντα ῥεῖ, Mar 02 '19 at 15:01
@AyushiSharma don't edit peoples answers into your question, it means that your code now doesn't exhibit the problem stated in your question which is a little confusing — Alan Birtles, Mar 02 '19 at 16:42

score 0 · Answer 1 · answered Mar 02 '19 at 14:41

Output to streams is usually buffered. Unless the buffer is flushed (which happens when you fill the buffer completely, or explicitly flush it) then the output won't actually be written.

The stream buffer is also flushed when the stream object is closed, which happens when std::cout is destructed as part of program termination. That's why you see the output when the program exits.

So the solution is simple: Explicitly flush the buffer (using e.g. std::cout.flush();) after each write.

πάντα ῥεῖ · Answer 2 · 2019-03-02T14:53:21.477

std::ostreamimplementations like std::cout work buffered usually. That means the std::ostream implementation collects what's passed with calls to write() in a buffer, and only if the buffer is exhausted, the actual contents will be sent to the physical device (a terminal, or a file manifested at the storage).

To trigger the stream writing the buffer contents to the terminal or a file, you explicitely have to call std::ostream::flush() (note that the std::endl I/O manipulator does that implicitely).

Prints string on console with cout.write() function only after I Quit the application

2 Answers2