snprintf(9)

💖 NAME

okay so welcome to snprintf(9), bestie — straight outta the Kernel API Manual ✨. This is the function that formats a string and places it in a buffer. iconic behavior, honestly 🎀.

✨ SYNOPSIS

int snprintf (char *buf , size_t size , const char *fmt , ... );

🎀 ARGUMENTS

• buf — the buffer to place the result into. that's the destination, bestie 🫶
• size — the size of the buffer, including the trailing null space. yes, the null terminator counts too — don't forget her 💅
• fmt — the format string to use. the blueprint, the vibe template 🌸
• ... — arguments for the format string. all the little extras that get formatted in 🔥

🌸 DESCRIPTION

The return value is literally the number of characters which would be generated for the given input, excluding the trailing null, as per ISO C99. so it's giving "how many characters the full output wanted," not just the part that fit 😌.

If the return is greater than or equal to size, the resulting string is truncated. truncated, bestie — the string got cut off at the buffer's edge 💀. not a cute look, but that's the rule.

For format string extensions over C99, see the vsnprintf documentation. that's where the extra format-string lore lives 👑.

🦋 SEE ALSO

Kernel file ./lib/vsprintf.c, plus the whole friend group:

• simple_strtoull(9)
• simple_strtoul(9)
• simple_strtol(9)
• simple_strtoll(9)
• vsnprintf(9)
• vscnprintf(9)
• scnprintf(9)
• vsprintf(9)
• sprintf(9)
• vbin_printf(9)
• bstr_printf(9)
• vsscanf(9)
• sscanf(9)

source/version ./lib · October 2026 · snprintf(9) — all accounted for, bestie. bye and go format responsibly 💅🫶