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

Since C++11

Header: <cstdlib>

Interprets an integer value in a byte string pointed to by str. The implied radix is always 10.

# Declarations

int atoi( const char* str );

long atol( const char* str );

long long atoll( const char* str );

(since C++11)

# Parameters

str: pointer to the null-terminated byte string to be interpreted

# Return value

Integer value corresponding to the contents of str on success.

# Example

#include <cstdlib>
#include <iostream>
 
int main()
{
    const auto data =
    {
        "42",
        "0x2A", // treated as "0" and junk "x2A", not as hexadecimal
        "3.14159",
        "31337 with words",
        "words and 2",
        "-012345",
        "10000000000" // note: out of int32_t range
    };
 
    for (const char* s : data)
    {
        const int i{std::atoi(s)};
        std::cout << "std::atoi('" << s << "') is " << i << '\n';
        if (const long long ll{std::atoll(s)}; i != ll)
            std::cout << "std::atoll('" << s << "') is " << ll << '\n';
    }
}