HP C/iX Library Reference Manual (30026-90004)

Chapter 5 351
HP C/iX Library Function Descriptions
strtod
strtod
Converts a string to a double-precision, floating-point number.
Syntax
#include <stdlib.h>
double strtod (const char * str , char ** ptr );
Parameters
str A pointer to a character string to be converted.
ptr If ptr is not NULL, a pointer to the character terminating the scan is stored
in the object pointed to by
ptr .
Return Values
x A double-precision floating-point number resulting from the successful
conversion of the string.
0 Indicates failure unless the value pointed to by
str is zero.
•If
*ptr is set to str , no number can be formed.
•If
*ptr is greater than str , the value pointed to by *str is zero.
•Iferrno is set to ERANGE, the correct value of the conversion would
cause an underflow.
±HUGE_VAL The conversion would cause an overflow; errno is set to ERANGE.
Description
The strtod() function returns as a double-precision, floating-point number the value
represented by the character string pointed to by
str. The string is scanned up to the first
unrecognizable character.
The string must contain a decimal constant or a floating-point constant that may
optionally be preceded by white space. The complete string may contain the following in
the order listed:
1. Optional white-space characters (as defined by isspace() ).
2. Optional sign.
3. Required string of digits, optionally containing a decimal point.
4. Optional e or E.
5. Optional sign or space.
6. Integer.