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

 

C++

Language

Standard library headers

Concepts

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

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

char_traits

 

std::basic_string

Member functions

basic_string::basic_string

basic_string::operator=

basic_string::assign

basic_string::get_allocator

Element access

basic_string::at

basic_string::operator[]

basic_string::front (C++11)

basic_string::back (C++11)

basic_string::data

basic_string::c_str

Iterators

basic_string::begin basic_string::cbegin (C++11)

basic_string::end basic_string::cend (C++11)

basic_string::rbegin basic_string::crbegin (C++11)

basic_string::rend basic_string::crend (C++11)

Capacity

basic_string::empty

basic_string::size

basic_string::length

basic_string::max_size

basic_string::reserve

basic_string::capacity

basic_string::shrink_to_fit (C++11)

Operations

basic_string::clear

basic_string::insert

basic_string::erase

basic_string::push_back

basic_string::pop_back (C++11)

basic_string::append

basic_string::operator+=

basic_string::compare

basic_string::replace

basic_string::substr

basic_string::copy

basic_string::resize

basic_string::swap

Search

basic_string::find

basic_string::rfind

basic_string::find_first_of

basic_string::find_first_not_of

basic_string::find_last_of

basic_string::find_last_not_of

Constants

basic_string::npos

Non-member functions

operator+

operator== operator!= operator< operator> operator<= operator>=

swap(std::basic_string)

operator<< operator>>

getline

stoi stol stoll (C++11) (C++11) (C++11)

stoul stoull (C++11) (C++11)

stof stod stold (C++11) (C++11) (C++11)

to_string (C++11)

to_wstring (C++11)

Helper classes

hash<std::string> hash<std::wstring> hash<std::u32string> hash<std::u16string> (C++11)

 

Defined in header <string>
int       stoi( const std::string& str, size_t *pos = 0, int base = 10 );	(1)	(since C++11)
long      stol( const std::string& str, size_t *pos = 0, int base = 10 );	(2)	(since C++11)
long long stoll( const std::string& str, size_t *pos = 0, int base = 10 );	(3)	(since C++11)

Interprets a signed integer value in the string str.

Function discards any whitespace characters (as identified by calling isspace()) 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. In non-default locales, additional numeric formats may be accepted.

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.

The index of the first unconverted character is stored in pos. If NULL is passed as pos, it is ignored.

Parameters

str	-	the string to convert
pos	-	address of an integer to store the index of the first unconverted character
base	-	the number base

Return value

The string converted to the specified signed integer type.

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.

Example

run this code

#include <iostream>
#include <string>
 
int main()
{
    std::string test = "45";
    int myint = stoi(test);
    std::cout << myint << '\n';
}

Output:

45

See also

atoi atol atoll	converts a byte string to an integer value (function)
stoul stoull (C++11) (C++11)	converts a string to an unsigned integer (function)
stof stod stold (C++11) (C++11) (C++11)	converts a string to an floating point value (function)
to_string (C++11)	converts an integral or floating point value to string (function)