几个语句while循环

Question

I'm trying to put another statement to end the while-loop with logical AND:

while ( (character != '\n') && ( i < 10 ) )

...the extra +10:th letters does not get stored in the array. But I can still type in input until pressing ENTER / '\n'.

What am I doing wrong? What happens with the 'extra input'?

This is the code:

char character;
char buffer[81];
int i = 0;

do
{
    character = getchar();
    buffer[i] = character;
    ++i;
} while ( (character != '\n') && (i < 10) );

buffer[i-1] = '\0';

Answer 1

The function getchar does not read directly from the keyboard. It reads from stdin . And in most cases what you have written on the keyboard will not end up in stdin until you press enter. This behavior is outside your control and is determined by the terminal you are using.

So your code basically works, except that you should change buffer[i-1] to buffer[i] . If you want to detect keypresses directly, then you will need different methods. There are no good functions in the standard library to do this, but here is an answer that gives you two options. https://stackoverflow.com/a/20349652/6699433

Answer 2

When the do-while loop stops, i becomes 10 in your case. Let's say your input was 0123456789 . The input does not contain \n so buffer[9] becomes '9' . Now, after that you are assigning buffer[i - 1] to \0 and buffer[9] becomes \0 .

You want buffer[i] = '\0' . Also, do not forget to check that i does not cross the buffer size.