user-0 提问: C语言中用scanf读数据经常出现问题，比如说读字符读进来之前的一个newline。这个问题有关输入流、缓冲区，但从来没有搞懂过，求教……

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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: scanf最后用空白符结尾时，scanf会跳过空白符去读下一个字符，并不是达到你去年\n的效果，你需要用getchar来接收掉 空白符包括空格，制表符，换行符，回车符和换页符

user: user-3
content: scanf("abc = %d",&abc); 用户必须这么输入 abc=10 =后面才是真正需要输入的整数 但是因为格式串中有格式以外的字符 所以 abc=都必须先输入然后才能输入整数。

user: user-3
content: scanf( "%d\n" );scanf 格式中的非格式字符，要求原样输入， 其中 空格，回车等空白字符字符，要求必须输入空白字符（空格，\t,\r,\n等） 所以不仅解决不了问题，还会增加问题