std::atoi, std::atol, std::atoll

From Cppreference

C++ Standard Library
Language Utilities library Strings library Containers library Algorithms library Iterators library Numerics library Input/output library Localizations library Regular expressions library (C++11) Atomic operations library (C++11) Thread support library (C++11)
Strings library
Narrow character strings Wide character strings Classes basic_string char_traits
Narrow null-terminated 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 strtol strtoul strtof String manipulation strcpy strncpy strcat strncat strxfrm String examination strlen strcmp strncmp strcoll strchr strrchr strspn strcspn strpbrk strstr strtok Memory manipulation memchr memcmp memset memcpy memmove Miscellaneous strerror

Defined in header <cstdlib>
int       atoi( const char *str );
long      atol( const char *str )
long long atoll( const char *str );		(C++11 feature)

Interprets an integer value in a character 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 integer number representation and converts them to integer value. The valid integer value consists of the following parts:

• (optional) plus or minus sign
• numeric digits

Contents 1 Parameters 2 Return value 3 Example 4 See also

[edit] Parameters

str

-

pointer to the null-terminated character string to be interpreted

[edit] Return value

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

This section is incomplete Reason: fix links to limits

[edit] Example

This section is incomplete

[edit] See also

strtol strtoll	converts a character string to an integer value (function)
strtoul strtoull	converts a character string to an unsigned integer value (function)