帮助scanf中的格式字符串

Question

Here's the statement:

int i;
scanf("%d ",&i);

Why does the space at the end of the format string causes scanf to accept two inputs instead of 1?

Answer 1

The space at the end of the format string tells scanf to eat whitespace after the first integer. It's not actually accepting a second input. When you do enter a second value, scanf sees that the whitespace is finished it returns, storing the first integer into your variable i. The "second input" is still in the standard input stream.