user-0 提问: 关于scanf()函数的理解（原创）

回复:
user: user-1
content: 引用 11 楼 laishangxiao 的回复:[quote=引用 1 楼 user-6 的回复:] (scanf("%s",e))&&(strlen(e)>10)，请问这句话什么意思？ 实际e的值为 "hello\000\200\322\376\267"  因为e是一个数组。 怕输入的太多   导致数组溢出吧   [/quote] 怕溢出可以用%9s

user: user-1
content: 引用 11 楼 laishangxiao 的回复:[quote=引用 1 楼 user-6 的回复:] (scanf("%s",e))&&(strlen(e)>10)，请问这句话什么意思？ 实际e的值为 "hello\000\200\322\376\267"  因为e是一个数组。 怕输入的太多   导致数组溢出吧   [/quote]  没有用的， &&前面如果已经溢出， 行为已经未定义。

user: user-0
content: 引用 1 楼 user-6 的回复:(scanf("%s",e))&&(strlen(e)>10)，请问这句话什么意思？ 实际e的值为 "hello\000\200\322\376\267"  因为e是一个数组。 怕输入的太多   导致数组溢出吧

user: user-0
content: 引用 8 楼 mujiok2003 的回复:另外getchar()返回int, 不要用char去接。 恩  试了下代码   getchar()会读入字符 然后转成ACSII码为int型 作为返回值

user: user-0
content: 引用 3 楼 truelance 的回复:[quote=引用 楼主 laishangxiao 的回复:] 首先我们知道scanf是一直读到空白符为止：包括 制表符，换行符，回车符，空格；读取成功后会自动将后面的这些字符清理。  这句话的理解是错误的。 C标准中的定义(7.19.6.2.9)是: The first character, if any, after the input item remains unread. 后面的字符不会自动清理，而是等读下一个%时才自动跳过不需要的空白。 而getchar()是不会跳过空白的，所以就把回车读出来了[/quote]  引用 3 楼 truelance 的回复:[quote=引用 楼主 laishangxiao 的回复:] 首先我们知道scanf是一直读到空白符为止：包括 制表符，换行符，回车符，空格；读取成功后会自动将后面的这些字符清理。  这句话的理解是错误的。 C标准中的定义(7.19.6.2.9)是: The first character, if any, after the input item remains unread. 后面的字符不会自动清理，而是等读下一个%时才自动跳过不需要的空白。 而getchar()是不会跳过空白的，所以就把回车读出来了[/quote] 恩   这样就好理解了

user: user-1
content: 另外getchar()返回int, 不要用char去接。

user: user-1
content: linux g++，输入hello回车后，其实是输入hello\n, 没有\r

user: user-1
content: fflush会清空输出流的缓冲， 会不会清空输入流的缓冲区则由实现决定。

user: user-2

user: user-3
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.    scanf  return the number of fields successfully converted and assigned; the return value does not include fields that were read but not assigned. A return value of 0 indicates that no fields were assigned. The return value is EOF for an error or if the end-of-file character or the end-of-string character is encountered in the first attempt to read a character.

user: user-4
content: 引用 楼主 laishangxiao 的回复:首先我们知道scanf是一直读到空白符为止：包括 制表符，换行符，回车符，空格；读取成功后会自动将后面的这些字符清理。  这句话的理解是错误的。 C标准中的定义(7.19.6.2.9)是: The first character, if any, after the input item remains unread. 后面的字符不会自动清理，而是等读下一个%时才自动跳过不需要的空白。 而getchar()是不会跳过空白的，所以就把回车读出来了

user: user-5
content: 事实上，scanf只要格式转换符不是%c，那么它是是直接跳过最前面的空白符的。然后根据格式串去匹配，而当读到不匹配的输入时，它把不匹配的输入，返回给输入流，并结束匹配，返回

user: user-6
content: (scanf("%s",e))&&(strlen(e)>10)，请问这句话什么意思？ 实际e的值为 "hello\000\200\322\376\267"  因为e是一个数组。