CODEWITHSUNDEEP
c++cscanf
Questioneer
Questioneer

Reputation: 793

Scanf understandings

I am going through some examples in a book I have and I have come to something I've never seen before nor understand:

scanf("%d-%d-%d-%d-%d", &prefix, &group, &publisher, &item, &check_digit);

This code is part of a program that asks the user to enter their ISBN number of a book and later on breaks down the ISBN into Prefix = x, Group = y, etc..

I have NEVER seen the hypens between the %d's. Does anyone see any point in this??

Thanks

Upvotes: 3

Views: 351

Answers (4)

wkl
wkl

Reputation: 80031

scanf takes a format string, so it's about what input it expects to see for input. The hyphens are for actual hyphens in the input. 1-2-3-4-5-6 would be valid input for this call, and give you prefix=1, group=2, etc.

Upvotes: 1

hochl
hochl

Reputation: 12960

It parses 5 numbers (matched by %d) with a dash between each two (the -). Each number is saved to a variable passed in as argument. See the manual for scanf and printf under Conversions.

Upvotes: 1

stefanB
stefanB

Reputation: 79910

The represent the actual parts of the string to be scanned.

For example your "%d-%d-%d-%d-%d" would work with something like "10-56-666-1-90".

Upvotes: 3

Xeo
Xeo

Reputation: 131867

"Pattern matching". If the input doesn't fit the specified pattern (also called format), it fails. So if you input anything else than INT-INT-INT-INT-INT (where INT is a placeholder for an integer you input), the input would be considered invalid.

Upvotes: 4

Related Questions