Question

I wrote the following program in the C and when I run it, I was surprised by looking at the output.

Here is the program

int main()
{    
       printf("\nab");
       printf("\bsi");    
       printf("\rha");    
}

The output is :- hai
whereas I was expecting “absiha” since \n is for new line, \b is for backspace(non erase) and \r is for carriage return. So I was expecting that curson would be at “i” character because \r has been applied but when I run it and saw the output I was totally surprised and confused. Can anyone please explain me the output?

Answer 1

Let’s take it one step at a time:

<new line>ab<backspace>si<carriage return>ha

First, handle the backspace. Note that even though it is “non-erase”, the next character to be output would overwrite what was backspaced over:

<new line>asi<carriage return>ha

Now, a carriage return means to go back to the beginning of the line. So the “ha” overwrites the “as” in “asi:

<new line>hai

Now, the cursor is currently sitting on the i, so the next character to be output would overwrite i.