user-0 提问: 关于scanf缓冲的一个问题。

回复:
user: user-1
content: Format Specification Fields: scanf and wscanf Functions A format specification has the following form:  % [width] [{h | l | I64 | L}]type  The format argument specifies the interpretation of the input and can contain one or more of the following:   White-space characters: blank (' '); tab ('\t'); or newline ('\n'). A white-space character causes scanf to read, but not store, all consecutive white-space characters in the input up to the next non–white-space character. One white-space character in the format matches any number (including 0) and combination of white-space characters in the input.   Non–white-space characters, except for the percent sign (%). A non–white-space character causes scanf to read, but not store, a matching non–white-space character. If the next character in stdin does not match, scanf terminates.   Format specifications, introduced by the percent sign (%). A format specification causes scanf to read and convert characters in the input into values of a specified type. The value is assigned to an argument in the argument list.  The format is read from left to right. Characters outside format specifications are expected to match the sequence of characters in stdin; the matching characters in stdin are scanned but not stored. If a character in stdin conflicts with the format specification, scanf terminates, and the character is left in stdin as if it had not been read.  When the first format specification is encountered, the value of the first input field is converted according to this specification and stored in the location that is specified by the first argument. The second format specification causes the second input field to be converted and stored in the second argument, and so on through the end of the format string.  An input field is defined as all characters up to the first white-space character (space, tab, or newline), or up to the first character that cannot be converted according to the format specification, or until the field width (if specified) is reached. If there are too many arguments for the given specifications, the extra arguments are evaluated but ignored. The results are unpredictable if there are not enough arguments for the format specification.  Each field of the format specification is a single character or a number signifying a particular format option. The type character, which appears after the last optional format field, determines whether the input field is interpreted as a character, a string, or a number.   The simplest format specification contains only the percent sign and a type character (for example, %s). If a percent sign (%) is followed by a character that has no meaning as a format-control character, that character and the following characters (up to the next percent sign) are treated as an ordinary sequence of characters, that is, a sequence of characters that must match the input. For example, to specify that a percent-sign character is to be input, use %%.  An asterisk (*) following the percent sign suppresses assignment of the next input field, which is interpreted as a field of the specified type. The field is scanned but not stored.

user: user-2
content: 看到原因了，第178行，少了%c

user: user-2
content: 我看控制选项是用scanf("%d"，..)的，这也会自动跳过'\n'等空白符。我猜测是输入的时候多输入的别的字符。

user: user-2
content: 引用 3 楼 kanoyami 的回复:使用了getchar()之后还是这样，是在scanf语句后面加一句吧。为什么用fflush不能刷掉这个呢？ 怎么会没用，你写个小程序测试一下就知道有用了，不加fflush(stdin)，那么程序直接退出，加了，需要再输入一次 int main() { 	char str[128] = {0}; 	scanf("%s",str); //	fflush(stdin); 	getchar();  	return 0; } 第60行的fflush(stdin)放错位置了，不知道是不是这个原因，应该放在scanf()之后，放在那也应该是fflush(stdout)。

user: user-0
content: 引用 1 楼 coding_hello 的回复:因为用scanf输入，会等待回车确认。这个回车就是多出来的输入。  如果之后跟着另一个scanf，只要不是%c的scanf，都会吞掉之前的回车，不会有问题。但是最后一个scanf还是有一个回车。  对于最后一个回车的情况，就调用个getchar()吧 使用了getchar()之后还是这样，是在scanf语句后面加一句吧。为什么用fflush不能刷掉这个呢？

user: user-3
content: 引用 1 楼 coding_hello 的回复:因为用scanf输入，会等待回车确认。这个回车就是多出来的输入。  如果之后跟着另一个scanf，只要不是%c的scanf，都会吞掉之前的回车，不会有问题。但是最后一个scanf还是有一个回车。  对于最后一个回车的情况，就调用个getchar()吧+1,原来写了一个类似的程序，然后让同学进行测试，修改了许多这种问题

user: user-4
content: 因为用scanf输入，会等待回车确认。这个回车就是多出来的输入。  如果之后跟着另一个scanf，只要不是%c的scanf，都会吞掉之前的回车，不会有问题。但是最后一个scanf还是有一个回车。  对于最后一个回车的情况，就调用个getchar()吧