I am passing an unsigned 8-bit int into sscanf. If I try format specifier %c (which should fit) I get complicated errors during compliation. However, if I use %hhd instead I don't get any errors. Is my little quick fix a bad idea for any reason?
thanks!!
10  11379  JosAH 11,448
Recognized Expert MVP
If the format specifier "%hhd" happens to work throw your C implementation away
because it's extremely non-compliant then.
kind regards,
Jos
Out of interest, what are the errors given when you use %c?
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().
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.
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.
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
Jos, I thought you had gotten a faster keyboard! Maybe it needs some lubrication... ;-)
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
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.
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