Decimals & Amounts

const UI = 1.5;
const raw = BigInt(Math.round(UI * 10 ** decimals));
 
const display = Number(raw) / 10 ** decimals;

pub fn to_raw(ui: f64, decimals: u8) -> Result<u64> {
    let factor = 10u64.pow(decimals as u32);
    let raw = (ui * factor as f64).round() as u64;
    Ok(raw)
}

import { createSolanaRpc, address } from "@solana/kit";
 
const rpc = createSolanaRpc("https://api.devnet.solana.com");
const mint = address("MINT_PUBKEY");
 
const { value } = await rpc.getAccountInfo(mint, { encoding: "jsonParsed" }).send();
const decimals = value?.data.parsed.info.decimals as number;
 
function toRawAmount(uiAmount: string, decimals: number): bigint {
  const [whole, frac = ""] = uiAmount.split(".");
  const padded = (frac + "0".repeat(decimals)).slice(0, decimals);
  return BigInt(whole + padded);
}
 
function toUiAmount(raw: bigint, decimals: number): string {
  const s = raw.toString().padStart(decimals + 1, "0");
  const whole = s.slice(0, -decimals) || "0";
  const frac = s.slice(-decimals).replace(/0+$/, "");
  return frac ? `${whole}.${frac}` : whole;
}
 
const raw = toRawAmount("2.5", decimals);
console.log("raw:", raw.toString());
console.log("ui:", toUiAmount(raw, decimals));

use anchor_lang::prelude::*;
use anchor_spl::token::{self, Token, TokenAccount, TransferChecked, Mint};
 
#[derive(Accounts)]
pub struct SafeTransfer<'info> {
    pub mint: Account<'info, Mint>,
    #[account(mut)]
    pub from: Account<'info, TokenAccount>,
    #[account(mut)]
    pub to: Account<'info, TokenAccount>,
    pub authority: Signer<'info>,
    pub token_program: Program<'info, Token>,
}
 
pub fn safe_transfer(ctx: Context<SafeTransfer>, amount: u64) -> Result<()> {
    let decimals = ctx.accounts.mint.decimals;
    let cpi = CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        TransferChecked {
            mint: ctx.accounts.mint.to_account_info(),
            from: ctx.accounts.from.to_account_info(),
            to: ctx.accounts.to.to_account_info(),
            authority: ctx.accounts.authority.to_account_info(),
        },
    );
    token::transfer_checked(cpi, amount, decimals)?;
    Ok(())
}

use anchor_lang::solana_program::program_error::ProgramError;
 
pub fn mul_scaled(a: u64, b: u64) -> Result<u64, ProgramError> {
    a.checked_mul(b).ok_or(ProgramError::InvalidArgument)
}