在字符串末尾使用退格符

Question

backspace escape character '\b' is used t bring the cursor one character back...so it must work like a backspace key on our keyboard.

cout<<"Learn c++\b!";

This gives normal expected result- Learn c+!

But when using \b as the last character

cout<<"Learn c++!\b";

The '!' is not erased output-Learn c++!

Instead i have to use

cout<<"Learn c++!\b \b";

to get the output-Learn c++

Can anybody tell the reason for such behavior..?

Answer 1

Your assumption:

so it must work like a backspace key

is not correct. \b moves the cursor one character backwards. It does not delete any characters. In an interactive terminal that leads to the effect you observed.

std::cout << "Hello, world\b!\n";

This starts with printing Hello, world , then moves the cursor 1 step to the left, then prints ! and moves to a new line, resulting in Hello, worl! .

std::cout << "Hello, world!\b\n";

This starts with printing Hello, world! , then moves the cursor 1 step to the left, then moves to a new line resulting in Hello, world! .

As the question comments already mentioned this overwriting effect only happens in a terminal. If you output to a file all the characters including the \b are preserved as is.