(7.3.1) The sets of characters tested for by the isalnum, isalpha, iscntrl, islower, isprint, and isupper functions:
Table E–6 Character Sets Tested by isalpha, islower, etc.|
isalnum |
ASCII characters A-Z, a-z and 0-9 |
|
isalpha |
ASCII characters A-Z and a-z, plus locale-specific single-byte letters |
|
iscntrl |
ASCII characters with value 0-31 and 127 |
|
islower |
ASCII characters a-z |
|
isprint |
Locale-specific single-byte printable characters |
|
isupper |
ASCII characters A-Z |
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