| Function | Implemented | C23 Standard Section | POSIX.1-2017 Standard Section |
|---|---|---|---|
| isalnum | |check| | 7.4.1.1 | |
| isalpha | |check| | 7.4.1.2 | |
| isblank | |check| | 7.4.1.3 | |
| iscntrl | |check| | 7.4.1.4 | |
| isdigit | |check| | 7.4.1.5 | |
| isgraph | |check| | 7.4.1.6 | |
| islower | |check| | 7.4.1.7 | |
| isprint | |check| | 7.4.1.8 | |
| ispunct | |check| | 7.4.1.9 | |
| isspace | |check| | 7.4.1.10 | |
| isupper | |check| | 7.4.1.11 | |
| isxdigit | |check| | 7.4.1.12 | |
| tolower | |check| | 7.4.2.1 | |
| toupper | |check| | 7.4.2.2 |