std::stoi, std::stol, std::stoll

Defined in header `<string>`
int stoi( const std::string& str, std::size_t* pos = nullptr, int base = 10 ); int stoi( const std::wstring& str, std::size_t* pos = nullptr, int base = 10 );	(1)	(since C++11)
long stol( const std::string& str, std::size_t* pos = nullptr, int base = 10 ); long stol( const std::wstring& str, std::size_t* pos = nullptr, int base = 10 );	(2)	(since C++11)
long long stoll( const std::string& str, std::size_t* pos = nullptr, int base = 10 ); long long stoll( const std::wstring& str, std::size_t* pos = nullptr, int base = 10 );	(3)	(since C++11)

Interprets a signed integer value in the string str.

1) calls std::strtol(str.c_str(), &ptr, base) or std::wcstol(str.c_str(), &ptr, base)

2) calls std::strtol(str.c_str(), &ptr, base) or std::wcstol(str.c_str(), &ptr, base)

3) calls std::strtoll(str.c_str(), &ptr, base) or std::wcstoll(str.c_str(), &ptr, base)

Discards any whitespace characters (as identified by calling std::isspace) until the first non-whitespace character is found, then 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 or 0)
(optional) prefix (0x or 0X) indicating hexadecimal base (applies only when the base is 16 or 0)
a sequence of digits

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 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.

Additional numeric formats may be accepted by the currently installed C locale.

If the value of base is 0, the numeric base is auto-detected: if the prefix is 0, the base is octal, if the prefix is 0x or 0X, 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 by unary minus in the result type.

If pos is not a null pointer, then a pointer ptr - internal to the conversion functions - will receive the address of the first unconverted character in str.c_str(), and the index of that character will be calculated and stored in *pos, giving the number of characters that were processed by the conversion.

Parameters

str	-	the string to convert
pos	-	address of an integer to store the number of characters processed
base	-	the number base

Return value

Integer value corresponding to the content of str.

Exceptions

std::invalid_argument if no conversion could be performed
std::out_of_range if the converted value would fall out of the range of the result type or if the underlying function (std::strtol or std::strtoll) sets errno to ERANGE.

Example

Run this code

#include <string>
#include <iomanip>
#include <utility>
#include <iostream>
#include <stdexcept>
 
int main()
{
    const auto data = {
        "45",
        "+45",
        " -45",
        "3.14159",
        "31337 with words",
        "words and 2",
        "12345678901",
    };
 
    for (const std::string s : data)
    {
        std::size_t pos{};
        try
        {
            std::cout << "std::stoi('" << s << "'): ";
            const int i {std::stoi(s, &pos)};
            std::cout << i << "; pos: " << pos << '\n';
        }
        catch(std::invalid_argument const& ex)
        {
            std::cout << "std::invalid_argument::what(): " << ex.what() << '\n';
        }
        catch(std::out_of_range const& ex)
        {
            std::cout << "std::out_of_range::what(): " << ex.what() << '\n';
            const long long ll {std::stoll(s, &pos)};
            std::cout << "std::stoll('" << s << "'): " << ll << "; pos: " << pos << '\n';
        }
    }
 
    std::cout << "\nCalling with different radixes:\n";
    for (const auto& [s, base]: { std::pair<const char*, int>
        {"11",  2}, {"22",  3}, {"33",  4}, {"77",  8},
        {"99", 10}, {"FF", 16}, {"jJ", 20}, {"Zz", 36}, })
    {
        const int i {std::stoi(s, nullptr, base)};
        std::cout << "std::stoi('" << s << "', " << base << "): " << i << '\n';
    }
}

Possible output:

std::stoi('45'): 45; pos: 2
std::stoi('+45'): 45; pos: 3
std::stoi(' -45'): -45; pos: 4
std::stoi('3.14159'): 3; pos: 1
std::stoi('31337 with words'): 31337; pos: 5
std::stoi('words and 2'): std::invalid_argument::what(): stoi
std::stoi('12345678901'): std::out_of_range::what(): stoi
std::stoll('12345678901'): 12345678901; pos: 11
 
Calling with different radixes:
std::stoi('11', 2): 3
std::stoi('22', 3): 8
std::stoi('33', 4): 15
std::stoi('77', 8): 63
std::stoi('99', 10): 99
std::stoi('FF', 16): 255
std::stoi('jJ', 20): 399
std::stoi('Zz', 36): 1295

Compiler support
Freestanding and hosted
Language
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Technical specifications
Symbols index
External libraries

Null-terminated strings
Byte strings
Multibyte strings
Wide strings
Classes
basic_string
basic_string_view (C++17)
char_traits

stoulstoull (C++11)(C++11)	converts a string to an unsigned integer (function)
stofstodstold (C++11)(C++11)(C++11)	converts a string to a floating point value (function)
strtolstrtoll (C++11)	converts a byte string to an integer value (function)
strtoulstrtoull (C++11)	converts a byte string to an unsigned integer value (function)
strtoimaxstrtoumax (C++11)(C++11)	converts a byte string to std::intmax_t or std::uintmax_t (function)
from_chars (C++17)	converts a character sequence to an integer or floating-point value (function)
atoiatolatoll (C++11)	converts a byte string to an integer value (function)
to_string (C++11)	converts an integral or floating point value to `string` (function)
to_wstring (C++11)	converts an integral or floating point value to `wstring` (function)

std::stoi, std::stol, std::stoll

Parameters

Return value

Exceptions

Example

See also

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