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| Conversions to and from numeric formats | |||||||||||||||||||||||||||||||||||||||||
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| String manipulation | |||||||||||||||||||||||||||||||||||||||||
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| String examination | |||||||||||||||||||||||||||||||||||||||||
| Memory manipulation | |||||||||||||||||||||||||||||||||||||||||
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| Miscellaneous | |||||||||||||||||||||||||||||||||||||||||
(C11)(C11) | |||||||||||||||||||||||||||||||||||||||||
Defined in header <stdlib.h> | ||
unsignedlong strtoul(constchar* str,char** str_end, int base); | (until C99) | |
unsignedlong strtoul(constchar*restrict str,char**restrict str_end, int base); | (since C99) | |
unsignedlonglong strtoull(constchar*restrict str,char**restrict str_end, int base); | (since C99) | |
Interprets an unsigned integer value in a byte string pointed to bystr.
Discards any whitespace characters (as identified by callingisspace) until the first non-whitespace character is found, then takes as many characters as possible to form a validbase-n (where n=base) unsigned integer number representation and converts them to an integer value. The valid unsigned integer value consists of the following parts:
0) indicating octal base (applies only when the base is8 or0)0x or0X) indicating hexadecimal base (applies only when the base is16 or0)The set of valid values for base is{0, 2, 3, ..., 36}. The set of valid digits for base-2 integers is{0, 1}, for base-3 integers is{0, 1, 2}, and so on. For bases larger than10, valid digits include alphabetic characters, starting fromAa for base-11 integer, toZz for base-36 integer. The case of the characters is ignored.
Additional numeric formats may be accepted by the currently installed Clocale.
If the value ofbase is0, the numeric base is auto-detected: if the prefix is0, the base is octal, if the prefix is0x or0X, the base is hexadecimal, otherwise the base is decimal.
If the minus sign was part of the input sequence, the numeric value calculated from the sequence of digits is negated as if byunary minus in the result type, which applies unsigned integer wraparound rules.
The functions sets the pointer pointed to bystr_end to point to the character past the last character interpreted. Ifstr_end is a null pointer, it is ignored.
Contents |
| str | - | pointer to the null-terminated byte string to be interpreted |
| str_end | - | pointer to a pointer to character, might be set to a position past the last character interpreted |
| base | - | base of the interpreted integer value |
Integer value corresponding to the contents ofstr on success. If the converted value falls out of range of corresponding return type, range error occurs (errno is set toERANGE) andULONG_MAX orULLONG_MAX is returned. If no conversion can be performed,0 is returned.
#include <errno.h>#include <stdio.h>#include <stdlib.h> int main(void){constchar* p="10 200000000000000000000000000000 30 -40 - 42";printf("Parsing '%s':\n", p);char* end=NULL;for(unsignedlong i= strtoul(p,&end,10); p!= end; i= strtoul(p,&end,10)){printf("'%.*s' -> ",(int)(end- p), p); p= end;if(errno==ERANGE){errno=0;printf("range error, got ");}printf("%lu\n", i);}printf("After the loop p points to '%s'\n", p);}
Output:
Parsing '10 200000000000000000000000000000 30 -40 - 42':'10' -> 10' 200000000000000000000000000000' -> range error, got 18446744073709551615' 30' -> 30' -40' -> 18446744073709551576After the loop p points to ' - 42'
(C95)(C99) | converts a wide string to an unsigned integer value (function)[edit] |
(C99) | converts a byte string to an integer value (function)[edit] |
(C99) | converts a byte string to an integer value (function)[edit] |
C++ documentation forstrtoul | |
