一、sscanf在直接处理逗号分隔符的时候，会发生错误。
程序如下：
- char *s = "aaa,bbb,ccc,ddd";
- char a[32],b[32],c[32],d[32];
- sscanf(s, "%s,%s,%s,%s\n", a, b, c, d);
- printf("[%s][%s][%s][%s]\n", a, b, c, d);
结果为:
- develop:/home/leon/test # ./a.out
- [aaa,bbb,ccc,ddd][][][]
二、解决。将sscanf内的格式化输出改为以下形式:
- sscanf(s, "%[^,],%[^,],%[^,],%s", a, b, c, d);
结果为:
- develop:/home/leon/test # ./a.out
- [aaa][bbb][ccc][ddd]
三、以下为MDSN的说明:
To read strings not delimited by space characters, a set of characters in brackets ([ ]) can be substituted for the s (string) type character. The corresponding input field is read up to the first character that does not appear in the bracketed character set. If the first character in the set is a caret (^), the effect is reversed: The input field is read up to the first character that does appear in the rest of the character set.
Note that %[a-z] and %[z-a] are interpreted as equivalent to %[abcde...z]. This is a common scanf function extension, but note that the ANSI standard does not require it.
理解:
%[] 指定字符集，即加了字符规则的'%s
^ 取反
%[^,] 取非','的内容,直到遇到','