kstrtoudec64(9)

💅 kstrtoudec64 💅

okay so bestie, welcome to kstrtoudec64 — the little kernel helper that takes a string and turns it into an unsigned 64-bit scaled decimal value. yes, that's the whole vibe. it's from the Kernel API Manual and honestly it ate. ✨

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🌸 SYNOPSIS 🌸

int kstrtoudec64 (const char *s , unsigned int scale , u64 *res );

like, three args, no drama, she's lowkey iconic for that 🫶

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🎀 ARGUMENTS 🎀

• s — the start of the string, bestie. it must be null-terminated, and it may also include a single newline before its terminating null (just the one, okay? don't get weird with it 🙈). the first character may also be a plus sign — but not a minus sign. nope. no negatives here, this is unsigned erasure 💀
• scale — the number of digits to the right of the decimal point. that's it, that's the whole job ✨
• res — where the result of the conversion gets written on success. it's the lil home for your answer 🏠💖

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🦋 DESCRIPTION 🦋

okay so let's do the example, because the example eats:

a scale of 3 with input "123.45" results in 123450. iconic. no cap. 🔥

and here's the tea: trailing zeros in the fractional part of the input, the ones you'd need to match the scale? not required. she's chill like that. 🧚

also — digits beyond the specified scale are ignored. literally just not invited to the party 🙅‍♀️

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💜 RETURN 💜

• 0 on success — slay 💅
• -ERANGE on overflow — she got too big for her boots 😭
• -EINVAL on parsing error — the string showed up not knowing the assignment 💀

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👑 SEE ALSO 👑

• Kernel file ./lib/kstrtox.c
• _parse_integer_limit(9)
• kstrtoull(9)
• kstrtoll(9)
• kstrtouint(9)
• kstrtoint(9)
• kstrtobool(9)
• kstrtodec64(9)

go read them, iykyk 🌈⭐

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and that's the page, bestie 🎀 this one lives under ./lib, dated October 2026, and it's part of the Kernel API Manual — periodt. 💖🦋🌸