Match zero or more spaces using sscanf

Question

Let's have this code

char input[] = "key: value";
char key[32], value[32];
sscanf(input, "%31[^:]:%*[ ]%31s", key, value);

There can be zero or more spaces after the :, I'd like to store the key ond value into c-string variables. The code above can work with one or more spaces, but tough luck with zero spaces.

Is there a simple way how to parse such strings? No necessarily sscanf, but I'd like to avoid regex.

Edit

I found a reference supporting the accepted answer (what an useful, but non-intuitive feature):

the function will read and ignore any whitespace characters encountered before the next non-whitespace character (whitespace characters include spaces, newline and tab characters -- see isspace). A single whitespace in the format string validates any quantity of whitespace characters extracted from the stream (including none).

possible duplicate of scanf format specifier to read zero or more characters from a set of characters — Paul Roub
@PaulRoub: the situations are related, but I think this is different from the possible duplicate. In particular, there is a simple solution to this question; I don't think there's an alternative to the 'try it twice if necessary' answer in the other question. — Jonathan Leffler
I would suggest using strstr to find the ':' replace the ':' with '\0' then strncpy() to get the first string. then using the previously acquired ptr to the '\0', step forward to the next non ' ' char, then perhaps sscanf() to retrieve that second string. Another method would be to use strtok() — user3629249

Jonathan Leffler Jonathan Leffler · Accepted Answer · 2014-12-22T23:35:34

Just use "%31[^:]:%31s".

The %s conversion specification skips leading blanks anyway, and stops at the first blank after one or more non-blanks.

If you decide you need blanks in the second field, but not the leading blanks, then use:

"%31[^:]: %31[^\001]"

(assuming it is unlikely that your string contains control-A characters that you're interested in). The blank in the format string skips zero or more blanks (strictly, zero or more white space characters).

Match zero or more spaces using sscanf

1 Answers