user-0 提问: 关于scanf函数的一个问题

回复:
user: user-1
content: printf里面的%和变量的一一对应关系 scanf里面的%和变量以及变量前加不加&的一一对应关系 是C代码中非常容易出错的地方，而且通常编译还不出错。 所以在编译源代码之前值得专门仔细检查一遍甚至多遍。

user: user-2
content: printf("%c",&a);

user: user-3
content: 转译了吧，就相当于int a = 'a';效果一样

user: user-4
content: %d读入一个有效数，遇非有效数字结束； %c读入一个字符，因接收对象a是int，所以接收到的字符会转换成ASCII码存放在变量a。 建议自己敲一下代码，结果一目了然。

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.  仅供参考：#include <stdio.h> char s[]="123 ab 4"; char *p; int v,n,k; void main() {     p=s;     while (1) {         k=sscanf(p,"%d%n",&v,&n);         printf("k,v,n=%d,%d,%d\n",k,v,n);         if (1==k) {             p+=n;         } else if (0==k) {             printf("skip char[%c]\n",p[0]);             p++;         } else {//EOF==k             break;         }     }     printf("End.\n"); } //k,v,n=1,123,3 //k,v,n=0,123,3 //skip char[ ] //k,v,n=0,123,3 //skip char[a] //k,v,n=0,123,3 //skip char[b] //k,v,n=1,4,2 //k,v,n=-1,4,2 //End.

user: user-5
content: 程序都写出来了，自己编译运行看看不就知道了？