###### (This is the documentation for SDL3, which is the current stable version. [SDL2](https://wiki.libsdl.org/SDL2/) was the previous version!) # SDL_isdigit Report if a character is a numeric digit. ## Header File Defined in [](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_stdinc.h) ## Syntax ```c int SDL_isdigit(int x); ``` ## Function Parameters | | | | | --- | ----- | ------------------------- | | int | **x** | character value to check. | ## Return Value (int) Returns non-zero if x falls within the character class, zero otherwise. ## Remarks **WARNING**: Regardless of system locale, this will only treat ASCII values '0' (0x30) through '9' (0x39), as true. ## Thread Safety It is safe to call this function from any thread. ## Version This function is available since SDL 3.1.3. ---- [CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryStdinc](CategoryStdinc)