6.30 Case Ranges
You can specify a range of consecutive values in a single case
label, like this:
case low ... high:
This has the same effect as the proper number of individual case
labels, one for each integer value from low to high, inclusive.
This feature is especially useful for ranges of ASCII character codes:
case 'A' ... 'Z':
Be careful: Write spaces around the ...
, for otherwise it may be parsed wrong when you use it with integer values. For example, write this:
case 1 ... 5:
rather than this:
case 1...5:
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Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Case-Ranges.html