doublearg, floatarg - parse floating-point value or ask user

#include <ctype.h>

double doublearg (ptr,brk,prompt,min,max,defalt);
const char **ptr,*brk,*prompt;
double min,max,defalt;

float floatarg (ptr,brk,prompt,min,max,defalt);
const char **ptr,*brk,*prompt;
float min,max,defalt;

Doublearg and floatarg attempt to parse an argument from a string,
passing the string pointer ptr and the break character seg brk to
the nxtarg(3) routine. If there is an argument parsed, and it is a
legal floating-point value between min and max, then it is returned
by doublearg or floatarg. If there is no argument, or if it is not
a valid floating-point number, or if it is out of range, then an
error message is printed and the routine getdouble(3) or
getfloat(3) is passed the remaining parameters; the value returned
by getdouble or getfloat is then returned by doublearg or floatarg.

Doublearg and floatarg are especially useful for parsing floating-
point values from argument lists in programs using the command
interpreter, ci(3).

nxtarg(3), getdouble(3), getfloat(3), ci(3)