user-0 提问: 每一个scanf后面都要加一个getchar来吸收换行符吗？

回复:
user: user-1
content: 程序碰到scanf函数时，不是直接要用户输入！而是先看缓冲区里面有没有东西，有的话，就读取一个字符出来(空格，换行，这些不可见的都属于被读取之列)。 所以如果你使用scanf("%c",&X), 那么，第一次X确实就是你输入的字符，但如果你的程序结构如下： scanf("%c",&X) while {   scanf("%c",&X); } 对于这种情况，那么你需要注意了，第二个scanf，直接从你上次输入的缓冲去读X的下一个字符(有可能是回车，如果你输入了一串的话，那就是第二个字符)。所以这时候，你只需要在第二个scanf后面加一句 if(X=='\n') scanf("%c",&X)，即程序结构改为： scanf("%c",&X) while {   scanf("%c",&X);   if(X=='\n') scanf("%c",&X); }  这样就基本满足你的程序需要了。 因为我们知道了scanf("%c"... 从缓冲区读数据的原理,所以变成的时候，刻意的把不需要的不可见字符去掉就可以，不管是换行还是空格之类的。。。

user: user-2
content: 引用 1 楼 zhao4zhong1 的回复:永远不要scanf("%c",...即可。为什么啊 老师

user: user-3
content: 某些情况不需要

user: user-4
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-4
content: 永远不要scanf("%c",...即可。