ecvt(3) [osx man page]
ECVT(3) BSD Library Functions Manual ECVT(3) NAME
ecvt, fcvt, gcvt -- convert double to ASCII string SYNOPSIS
#include <stdlib.h> char * ecvt(double value, int ndigit, int * restrict decpt, int * restrict sign); char * fcvt(double value, int ndigit, int * restrict decpt, int * restrict sign); char * gcvt(double value, int ndigit, char *buf); DESCRIPTION
These functions are provided for compatibility with legacy code. New code should use the snprintf(3) function for improved safety and porta- bility. The ecvt(), fcvt() and gcvt() functions convert the double precision floating-point number value to a NUL-terminated ASCII string. The ecvt() function converts value to a NUL-terminated string of exactly ndigit digits and returns a pointer to that string. The result is padded with zeroes from left to right as needed. There are no leading zeroes unless value itself is 0. The least significant digit is rounded in an implementation-dependent manner. The position of the decimal point relative to the beginning of the string is stored in decpt. A negative value indicates that the decimal point is located to the left of the returned digits (this occurs when there is no whole number component to value). If value is zero, it is unspecified whether the integer pointed to by decpt will be 0 or 1. The decimal point itself is not included in the returned string. If the sign of the result is negative, the integer pointed to by sign is non-zero; otherwise, it is 0. If the converted value is out of range or is not representable, the contents of the returned string are unspecified. The fcvt() function is identical to ecvt() with the exception that ndigit specifies the number of digits after the decimal point (zero-padded as needed). The gcvt() function converts value to a NUL-terminated string similar to the %g printf(3) format specifier and stores the result in buf. It produces ndigit significant digits similar to the %f printf(3) format specifier where possible. If ndigit does allow sufficient precision, the result is stored in exponential notation similar to the %e printf(3) format specifier. If value is less than zero, buf will be prefixed with a minus sign. A decimal point is included in the returned string if value is not a whole number. Unlike the ecvt() and fcvt() func- tions, buf is not zero-padded. RETURN VALUES
The ecvt(), fcvt() and gcvt() functions return a NUL-terminated string representation of value. WARNINGS
The ecvt() and fcvt() functions return a pointer to internal storage space that will be overwritten by subsequent calls to either function. The maximum possible precision of the return value is limited by the precision of a double and may not be the same on all architectures. The snprintf(3) function is preferred over these functions for new code. SEE ALSO
printf(3), strtod(3) STANDARDS
The ecvt(), fcvt() and gcvt() functions conform to IEEE Std 1003.1-2001 (``POSIX.1''). BSD
May 31, 2007 BSD
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ecvt(3C) Standard C Library Functions ecvt(3C) NAME
ecvt, fcvt, gcvt - convert floating-point number to string SYNOPSIS
#include <stdlib.h> char *ecvt(double value, int ndigit, int *restrict decpt, int *restrict sign); char *fcvt(double value, int ndigit, int *restrict decpt, int *restrict sign); char *gcvt(double value, int ndigit, char *buf); DESCRIPTION
The ecvt(), fcvt() and gcvt() functions convert floating-point numbers to null-terminated strings. ecvt() The ecvt() function converts value to a null-terminated string of ndigit digits (where ndigit is reduced to an unspecified limit determined by the precision of a double) and returns a pointer to the string. The high-order digit is non-zero, unless the value is 0. The low-order digit is rounded. The position of the radix character relative to the beginning of the string is stored in the integer pointed to by decpt (negative means to the left of the returned digits). The radix character is not included in the returned string. If the sign of the result is negative, the integer pointed to by sign is non-zero, otherwise it is 0. If the converted value is out of range or is not representable, the contents of the returned string are unspecified. fcvt() The fcvt() function is identical to ecvt() except that ndigit specifies the number of digits desired after the radix point. The total num- ber of digits in the result string is restricted to an unspecified limit as determined by the precision of a double. gcvt() The gcvt() function converts value to a null-terminated string (similar to that of the %g format of printf(3C)) in the array pointed to by buf and returns buf. It produces ndigit significant digits (limited to an unspecified value determined by the precision of a double) in %f if possible, or %e (scientific notation) otherwise. A minus sign is included in the returned string if value is less than 0. A radix character is included in the returned string if value is not a whole number. Trailing zeros are suppressed where value is not a whole num- ber. The radix character is determined by the current locale. If setlocale(3C) has not been called successfully, the default locale, POSIX, is used. The default locale specifies a period (.) as the radix character. The LC_NUMERIC category determines the value of the radix character within the current locale. RETURN VALUES
The ecvt() and fcvt() functions return a pointer to a null-terminated string of digits. The gcvt() function returns buf. ERRORS
No errors are defined. USAGE
The return values from ecvt() and fcvt() might point to thread-specific data that can be overwritten by subsequent calls to these functions by the same thread. For portability to implementations conforming to earlier versions of Solaris, sprintf(3C) is preferred over this function. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ SEE ALSO
printf(3C), setlocale(3C), sprintf(3C), attributes(5), standards(5) SunOS 5.11 18 May 2004 ecvt(3C)