3.2 Numeric Types
The basic integer types at various sizes. The s or u prefix specifies a signed or an unsigned integer, respectively; the ones with no prefix are signed.
Aliases for basic integer types. The _byte aliases correspond to _int8. The _short and _word aliases correspond to _int16. The _int aliases correspond to _int32. The _long aliases correspond to either _int32 or _int64, depending on the platform.
For cases where speed matters and where you know that the integer is small enough, the types _fixnum and _ufixnum are similar to _long and _ulong but assume that the quantities fit in PLT Scheme’s immediate integers (i.e., not bignums).
Like _fixnum and _ufixnum, but coercions from C are checked to be in range.
The _float and _double types represent the corresponding C types. The type _double* that implicitly coerces any real number to a C double.