strtol, strtoll

 

C

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Strings library

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Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C++11)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoi atol atoll strtol strtoll	strtoul strtoull strtof strtod strtold
String manipulation
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strncat
strxfrm
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strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
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memchr
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strerror

 

Defined in header <stdlib.h>
long      strtol( const char *str, char **str_end, int base );
long long strtoll( const char *str, char **str_end, int base );		(since C99)

Interprets an integer value in a byte string pointed to by str.

Function discards any whitespace characters until first non-whitespace character is found. Then it takes as many characters as possible to form a valid base-n (where n=base) integer number representation and converts them to an integer value. The valid integer value consists of the following parts:

• (optional) plus or minus sign
• (optional) prefix (0) indicating octal base (applies only when the base is 8)
• (optional) prefix (0x or 0X) indicating hexadecimal base (applies only when the base is 16)
• a sequence of digits

The set of valid digits for base-2 integer is 01, for base-3 integer is 012, and so on. For bases larger than 10, valid digits include alphabetic characters, starting from Aa for base-11 integer, to Zz for base-36 integer. The case of the characters is ignored.

The functions sets the pointer pointed to by str_end to point to the character past the last character interpreted. If str_end is NULL, it is ignored.

Parameters

str	-	pointer to the null-terminated byte string to be interpreted
str_end	-	pointer to a pointer to character.
base	-	base of the interpreted integer value

Return value

Integer value corresponding to the contents of str on success. If the converted value falls out of range of corresponding return type, range error occurs and LONG_MAX, LONG_MIN, LLONG_MAX or LLONG_MIN is returned. If no conversion can be performed, ​0​ is returned.

See also

atoi atol atoll	converts a byte string to an integer value (function)
strtoul strtoull	converts a byte string to an unsigned integer value (function)
C++ documentation for strtol, strtoll