sscanf print format problem - %hhd

424

Contributor

I can see three scenarios,

You're scanning a string for a character. You use %c in the format specifier and provide a short int.
Then character will be silently cast to a short int. The short int you provided will be assigned the ASCII value of the character, as expected.
You're scanning a string for a non-numeric character. You use %hhd in the format specifier and provide a short int.
Probably %hhd is interpreted as %hd which means short int (since h is the "short" modifier, presumably more than one modifier is ignored although this is bad practice). In this case, scanf will not find any numeric character which can be interpreted as a short int in the string provided. Nothing will be assigned to the short int which will retain its previous value.
You're scanning a string for a numeric character. You use %hhd in the format specifier and provide a short int.
Assuming %hhd means %hd, scanf will assign the number to the short int.

In any case, if there are errors it shouldn't be directly because of scanf().

Nov 14 '08 #4

dissectcode

New Member

Hi - The error I get if I try %c for my 8-bit unsigned int is:

error: duplicate case value
error: previously used here
error: duplicate case value

at specific lines, over and over again, and it won't compile.

I do not understand why I can't scan it properly. I have been stuck with this warning, not knowing how to fix it for months now.

Nov 14 '08 #5

424

Contributor

Are you using switch statements? Note then that all cases should be unique - maybe the result of the scanf is causing two cases to be the same. Perhaps you could give us an example of a line where this error occurs.

Nov 14 '08 #6

JosAH

11,448

Recognized Expert MVP

Hi - The error I get if I try %c for my 8-bit unsigned int is:

error: duplicate case value
error: previously used here
error: duplicate case value

at specific lines, over and over again, and it won't compile.

I do not understand why I can't scan it properly. I have been stuck with this warning, not knowing how to fix it for months now.

Those error messages indicate that you're using a switch statement somewhere.
Such a statement has nothing to do with a scanf() functions call. Can you show
us the code that uses the scanf() call as well as that switch statement?

kind regards,

Jos

Nov 14 '08 #7

424

Contributor

Jos, I thought you had gotten a faster keyboard! Maybe it needs some lubrication... ;-)

Nov 14 '08 #8

JosAH

11,448

Recognized Expert MVP

Jos, I thought you had gotten a faster keyboard! Maybe it needs some lubrication... ;-)

I know; I'm so speedy today ;-) especially when it comes to questions that divert
from their original goal. I wonder what source code comes up ...

kind regards,

Jos

Nov 14 '08 #9

newb16

687

Contributor

Are you using switch statements? Note then that all cases should be unique - maybe the result of the scanf is causing two cases to be the same. Perhaps you could give us an example of a line where this error occurs.

Result of scanf can appear only in runtime and has nothing to do with compile error.

Nov 14 '08 #10

print format for binary representation

424

Contributor

Yes, I agree it does sound a bit fishy... That's why I'd like to see some code.

Nov 14 '08 #11

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