std::wcstoi...d::wcstoumax(3)

💅 std::wcstoimax, std::wcstoumax 💅

okay bestie, welcome to the C++ Standard Library manual page for std::wcstoimax and std::wcstoumax — yes that's the whole name up top, it's giving "my parents gave me a long name and I'm thriving" energy ✨

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🎀 NAME 🎀

std::wcstoimax, std::wcstoumax — literally just std::wcstoimax and std::wcstoumax, that's it, that's the name 🫶

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✨ SYNOPSIS ✨

These two live in the header <cinttypes> (manifesting that for you rn 🕯️):

std::intmax_t wcstoimax( const wchar_t* nptr, wchar_t** endptr, int base );

(since C++11)

std::uintmax_t wcstoumax( const wchar_t* nptr, wchar_t** endptr, int base );

(since C++11)

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🌸 DESCRIPTION 🌸

So what do these actually do? They interpret an unsigned integer value in a wide string pointed to by nptr. Main character behavior, honestly 👑

Here's the whole ritual, step by step:

• It discards any whitespace characters (as identified by calling std::iswspace) until the first non-whitespace character is found 🔍
• Then it takes as many characters as possible to form a valid base-n (where n=base) unsigned integer number representation, and converts them to an integer value.

And that valid unsigned integer value is made of these parts, in order:

• (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} — no cap, we love a range 🦋 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. And the case of the characters is ignored — she's not picky 💅

Additional numeric formats may be accepted by the currently installed C locale. (iykyk, locale stuff is its own whole vibe 🙈)

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

And here's the spicy part 🌶️ — 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, which applies unsigned integer wraparound rules. Not me warning you about wraparound 😭 that's just how it be.

The functions set the pointer pointed to by endptr to point to the wide character past the last character interpreted. If endptr is a null pointer, it is ignored — she simply doesn't see it 🫥

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🧚 PARAMETERS 🧚

• nptr — pointer to the null-terminated wide string to be interpreted
• endptr — pointer to a pointer to a wide character
• base — base of the interpreted integer value

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👑 RETURN VALUE 👑

Integer value corresponding to the contents of str on success 💖

But if the converted value falls out of range of corresponding return type, range error occurs and INTMAX_MAX, INTMAX_MIN, UINTMAX_MAX, or 0 is returned, as appropriate. And if no conversion can be performed, 0 is returned. Not the vibe, but it's the documented vibe 💀

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🌈 EXAMPLE 🌈

Run this code, it's iconic:

#include <cinttypes>
#include <iostream>
#include <string>

int main()
{
    std::wstring str = L"helloworld";
    std::intmax_t val = std::wcstoimax(str.c_str(), nullptr, 36);
    std::wcout << str << " in base 36 is " << val << " in base 10\n";

    wchar_t* nptr;
    val = std::wcstoimax(str.c_str(), &nptr, 30);
    if (nptr != &str[0] + str.size())
        std::wcout << str << " in base 30 is invalid."
                   << " The first invalid digit is " << *nptr << '\n';
}

⭐ Output ⭐

helloworld in base 36 is 1767707668033969 in base 10
helloworld in base 30 is invalid. The first invalid digit is w

the way helloworld is a valid base-36 number and also a base-30 fail… ate and left no crumbs 🍓

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🦋 SEE ALSO 🦋

• strtoimax — (function)
• strtoumax — converts a byte string to std::intmax_t or std::uintmax_t (C++11) (function)
• wcstol — converts a wide string to an integer value (function)
• wcstoll — (function)
• wcstoul — converts a wide string to an unsigned integer value (function)
• wcstoull — (function)
• C documentation for wcstoimax, wcstoumax

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and that's the page bestie!! fr fr, go parse some wide strings, you're gonna slay 💜

mwah 💋 — sourced from http://cppreference.com, dated 2024.06.10, C++ Standard Library, and this manual page name std::wcstoi...d::wcstoumax(3) which we are respectfully abbreviating because bestie, nobody's reading that whole thing out loud 🎀