# FreeBSD Manual Pages

STRTOD(3) Library functions STRTOD(3)NAMEstrtod, strtof, strtold - convert ASCII string to floating point numberSYNOPSIS#include<stdlib.h>doublestrtod(constchar*nptr,char**endptr);floatstrtof(constchar*nptr,char**endptr);longdoublestrtold(constchar*nptr,char**endptr);DESCRIPTIONThestrtod,strtof, andstrtoldfunctions convert the initial portion of the string pointed to bynptrtodouble,float, andlongdoublerep- resentation, respectively. The expected form of the (initial portion of the) string is optional leading white space as recognized byisspace(3), an optional plus (``+'') or minus sign (``-'') and then either (i) a decimal number, or (ii) a hexadecimal number, or (iii) an infinity, or (iv) a NAN (not-a- number). Adecimalnumberconsists of a nonempty sequence of decimal digits pos- sibly containing a radix character (decimal point, locale dependent, usually ``.''), optionally followed by a decimal exponent. A decimal exponent consists of an ``E'' or ``e'', followed by an optional plus or minus sign, followed by a non-empty sequence of decimal digits, and indicates multiplication by a power of 10. Ahexadecimalnumberconsists of a ``0x'' or ``0X'' followed by a nonempty sequence of hexadecimal digits possibly containing a radix character, optionally followed by a binary exponent. A binary exponent consists of a ``P'' or ``p'', followed by an optional plus or minus sign, followed by a non-empty sequence of decimal digits, and indicates multiplication by a power of 2. At least one of radix character and binary exponent must be present. Aninfinityis either ``INF'' or ``INFINITY'', disregarding case. ANANis ``NAN'' (disregarding case) optionally followed by `(', a sequence of characters, followed by ')'. The character string speci- fies in an implementation-dependent way the type of NAN.RETURN VALUEThese functions return the converted value, if any. Ifendptris notNULL, a pointer to the character after the last char- acter used in the conversion is stored in the location referenced byendptr. If no conversion is performed, zero is returned and the value ofnptris stored in the location referenced byendptr. If the correct value would cause overflow, plus or minusHUGE_VAL(HUGE_VALF,HUGE_VALL) is returned (according to the sign of the value), andERANGEis stored inerrno. If the correct value would cause underflow, zero is returned andERANGEis stored inerrno.ERRORSERANGEOverflow or underflow occurred.CONFORMING TOANSI C describesstrtod, C99 describes the other two functions.SEE ALSOatof(3),atoi(3),atol(3),strtol(3),strtoul(3) Linux 2001-06-07 STRTOD(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | SEE ALSO

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