int MLPutReal32(MLINKlink, double x) puts the single-precision floating-point number x to the MathLink connection specified by link with a precision corresponding to the C type float.
The argument x is typically declared as float in external programs, but must be declared as double in MLPutReal32() itself in order to work even in the absence of C prototypes.
MLPutReal32() returns 0 in the event of an error, and a nonzero value if the function succeeds.
Use MLError() to retrieve the error code if MLPutReal32() fails.
MLPutReal32() is declared in the MathLink header file mathlink.h.