CODEWITHSUNDEEP
cstringparsingscanf
Jan Turoň
Jan Turoň

Reputation: 32912

Match zero or more spaces using sscanf

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).

Upvotes: 2

Views: 1879

Answers (1)

Jonathan Leffler
Jonathan Leffler

Reputation: 754550

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).

Upvotes: 6

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