Report if a character is a numeric digit.
**WARNING**: Regardless of system locale, this will only treat ASCII values '0' (0x30) through '9' (0x39), as true.
\param x character value to check. \returns non-zero if x falls within the character class, zero otherwise.
\threadsafety It is safe to call this function from any thread.
\since This function is available since SDL 3.2.0.
See Implementation
Report if a character is a numeric digit.
**WARNING**: Regardless of system locale, this will only treat ASCII values '0' (0x30) through '9' (0x39), as true.
\param x character value to check. \returns non-zero if x falls within the character class, zero otherwise.
\threadsafety It is safe to call this function from any thread.
\since This function is available since SDL 3.2.0.