If you are using decimal floating-point formats in your programs, use the -qdfp option when you compile them. For example, to compile the following Hello World program dfp_hello.c, the compiler invocation is:
xlc -qdfp dfp_hello.c
#include <stdio.h>
#include <float.h>
int main() {
printf("Hello DFP World\n");
printf("DEC32_MAX = %Hf\n",DEC32_MAX);
float f = 12.34df;
printf("12.34df as a float = %f\n",f);
}