strtoul(3) [redhat man page]
STRTOUL(3) Linux Programmer's Manual STRTOUL(3) NAME
strtoul, strtoull, strtouq - convert a string to an unsigned long integer SYNOPSIS
#include <stdlib.h> unsigned long int strtoul(const char *nptr, char **endptr, int base); unsigned long long int strtoull(const char *nptr, char **endptr, int base); DESCRIPTION
The strtoul() function converts the initial part of the string in nptr to an unsigned long integer value according to the given base, which must be between 2 and 36 inclusive, or be the special value 0. The string must begin with an arbitrary amount of white space (as determined by isspace(3)) followed by a single optional `+' or `-' sign. If base is zero or 16, the string may then include a `0x' prefix, and the number will be read in base 16; otherwise, a zero base is taken as 10 (decimal) unless the next character is `0', in which case it is taken as 8 (octal). The remainder of the string is converted to an unsigned long int value in the obvious manner, stopping at the first character which is not a valid digit in the given base. (In bases above 10, the letter `A' in either upper or lower case represents 10, `B' represents 11, and so forth, with `Z' representing 35.) If endptr is not NULL, strtoul() stores the address of the first invalid character in *endptr. If there were no digits at all, strtoul() stores the original value of nptr in *endptr (and returns 0). In particular, if *nptr is not ` ' but **endptr is ` ' on return, the entire string is valid. The strtoull() function works just like the strtoul() function but returns an unsigned long long integer value. RETURN VALUE
The strtoul() function returns either the result of the conversion or, if there was a leading minus sign, the negation of the result of the conversion, unless the original (non-negated) value would overflow; in the latter case, strtoul() returns ULONG_MAX and sets the global variable errno to ERANGE. Precisely the same holds for strtoull() (with ULLONG_MAX instead of ULONG_MAX). ERRORS
ERANGE The resulting value was out of range. EINVAL (not in C99) The given base contains an unsupported value. The implementation may also set errno to EINVAL in case no conversion was performed (no digits seen, and 0 returned). NOTES
In locales other than the "C" locale, also other strings may be accepted. (For example, the thousands separator of the current locale may be supported.) BSD also has u_quad_t strtouq(const char *nptr, char **endptr, int base); with completely analogous definition. Depending on the wordsize of the current architecture, this may be equivalent to strtoull() or to strtoul(). CONFORMING TO
strtoul() conforms to SVID 3, BSD 4.3, ISO 9899 (C99) and POSIX, and strtoull() to ISO 9899 (C99) and POSIX-2001. SEE ALSO
atof(3), atoi(3), atol(3), strtod(3), strtol(3) GNU
2002-05-30 STRTOUL(3)
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STRTOUL(3) BSD Library Functions Manual STRTOUL(3) NAME
strtoul, strtoull, strtoumax, strtouq -- convert a string to an unsigned long, unsigned long long, uintmax_t, or u_quad_t integer LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <stdlib.h> #include <limits.h> unsigned long strtoul(const char * restrict nptr, char ** restrict endptr, int base); unsigned long long strtoull(const char * restrict nptr, char ** restrict endptr, int base); #include <inttypes.h> uintmax_t strtoumax(const char * restrict nptr, char ** restrict endptr, int base); #include <sys/types.h> #include <stdlib.h> #include <limits.h> u_quad_t strtouq(const char *nptr, char **endptr, int base); DESCRIPTION
The strtoul() function converts the string in nptr to an unsigned long value. The strtoull() function converts the string in nptr to an unsigned long long value. The strtoumax() function converts the string in nptr to an uintmax_t value. The strtouq() function converts the string in nptr to a u_quad_t value. The conversion is done according to the given base, which must be between 2 and 36 inclusive, or be the special value 0. The string may begin with an arbitrary amount of white space (as determined by isspace(3)) followed by a single optional '+' or '-' sign. If base is zero or 16, the string may then include a ``0x'' prefix, and the number will be read in base 16; otherwise, a zero base is taken as 10 (decimal) unless the next character is '0', in which case it is taken as 8 (octal). The remainder of the string is converted to an unsigned long value in the obvious manner, stopping at the end of the string or at the first character that does not produce a valid digit in the given base. (In bases above 10, the letter 'A' in either upper or lower case represents 10, 'B' represents 11, and so forth, with 'Z' representing 35.) If endptr is not NULL, strtoul() stores the address of the first invalid character in *endptr. If there were no digits at all, however, strtoul() stores the original value of nptr in *endptr. (Thus, if *nptr is not ' ' but **endptr is ' ' on return, the entire string was valid.) RETURN VALUES
The strtoul(), strtoull(), strtoumax() and strtouq() functions return either the result of the conversion or, if there was a leading minus sign, the negation of the result of the conversion, unless the original (non-negated) value would overflow; in the latter case, strtoul() returns ULONG_MAX, strtoull() returns ULLONG_MAX, strtoumax() returns UINTMAX_MAX, and strtouq() returns ULLONG_MAX. In all cases, errno is set to ERANGE. If no conversion could be performed, 0 is returned and the global variable errno is set to EINVAL (the last feature is not portable across all platforms). ERRORS
[EINVAL] The value of base is not supported or no conversion could be performed (the last feature is not portable across all plat- forms). [ERANGE] The given string was out of range; the value converted has been clamped. SEE ALSO
strtol(3), strtonum(3), wcstoul(3) STANDARDS
The strtoul() function conforms to ISO/IEC 9899:1990 (``ISO C90''). The strtoull() and strtoumax() functions conform to ISO/IEC 9899:1999 (``ISO C99''). The BSD strtouq() function is deprecated. BSD
November 28, 2001 BSD