C Strings and my slow descent to madness

Re:C Strings and my slow descent to madness by torstenvl on Thursday April 06, 2023 @10:06AM (#35468480)

> You can printf non-null terminated strings too. Check printf("%.s", length, strptr).*

I haven't checked yet, but I'm about 90% confident that's UB. Is printf() guaranteed not to read to the end of the string when you give it a length?

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Re:C Strings and my slow descent to madness by nwellnhof on Thursday April 06, 2023 @10:32AM (#35468792)

Yes, it is. From the C11 spec:

> Characters from the array are written up to (but not including) the terminating null character. If the precision is specified, no more than that many bytes are written. If the precision is not specified or is greater than the size of the array, the array shall contain a null character.

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Re:C Strings and my slow descent to madness by torstenvl on Friday April 07, 2023 @09:37AM (#35481431)

Thanks! I guess I didn't realize expressio unius est exclusio alterius applies in the C standard :D

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Re:C Strings and my slow descent to madness by habibur on Thursday April 06, 2023 @12:54PM (#35471119)

Won't read a single byte beyond the length you give it.

And this is a standard practice in libraries for printing pre-determined lengthed string.

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