Flush cout output carefully

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shabbir ( Go4Expert Founder )

Shabbir is a developer in the field of Applications, web as well as database designing and is devoted to the optimization and usability of the code. He maintains Programming forum and is a C++ addict.

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When you compile the following code in VS 6 you get the output as

#include <iostream.h>
#include <stdio.h>
void main()
{
  cout<<"hello";
  printf("hi");
}

hihello

The reason behind this is cout is not flushed and you can get the desired out put by doing

#include <iostream.h>
#include <stdio.h>
void main()
{
  cout<<"hello";
  flush(cout);
  printf("hi");
}

You can also use the <<endl; to flush the output after each cout but keep in mind that flushing the output can degrade performance.

Thanks
Shabbir Bhimani

[AhmedHan]

Wov, that's really interesting.

In which header flush() is defined in? stdio.h or iostream.h?

[shabbir]

Originally Posted by AhmedHan

Wov, that's really interesting.

In which header flush() is defined in? stdio.h or iostream.h?

Both.

[DaWei]

I might mention that iostream.h is deprecated and is provided for backward compatibility. One should use iostream without an extension. The phenomenon occurs because cout and printf use two different streams; they may, however, be synced. It is generally not good practice to mix the two forms.

[DaWei]

Forgot to mention that "void main" is non-standard code. The standard specifies that main return an int. Some compilers, particularly less compliant ones, accept the void specification, but its use is non-standard and not recommended practice.

[shabbir]

Originally Posted by DaWei

I might mention that iostream.h is deprecated and is provided for backward compatibility. One should use iostream without an extension. The phenomenon occurs because cout and printf use two different streams; they may, however, be synced. It is generally not good practice to mix the two forms.

Originally Posted by DaWei

Forgot to mention that "void main" is non-standard code. The standard specifies that main return an int. Some compilers, particularly less compliant ones, accept the void specification, but its use is non-standard and not recommended practice.

Both the points well accepted.

[rahul.mca2001]

i will try to use flush now