basic/demo/demo_std.bas · 8441 字节 · 下载原文
' demo_std.bas —— BASIC 第一层：**标准输入输出**（std）
' demo_std.bas -- BASIC layer one: **standard input/output** (std)
'
' 这一层只用语言自己的 `PRINT`，不碰任何图形 / 控制台 / 宿主 UI 接口 ——
' This layer uses only the language's own `PRINT` and touches no graphics / console / host UI API --
' 所以它在**任何**后端上都是同一份行为，也是四份 demo 里唯一有
' so it behaves identically on **any** backend, and it is the only one of the four demos that has
' "逐字节确定性输出" 判据的一份（另外三份只能验"编得过、跑得完、不挂死"）。
' a "byte-for-byte deterministic output" probe (the other three can only be checked for "it compiles, it finishes, it does not hang").
'
' 跑法（桌面 vmlcli）：
' How to run it (desktop vmlcli):
' dotnet scripts/vmlcli/bin/Release/net10.0/vmlcli.dll Examples/basic/demo_std.bas
'
' 期望输出（逐字节，见文件末尾的 `demo_std.expected.txt` 对拍脚本）：
' Expected output (byte for byte; see the `demo_std.expected.txt` diff script at the end of the file):
' === BASIC 标准输出 demo ===
' === BASIC standard-output demo ===
' 字符串: 你好，世界
' string: hello, world (the label and the text are printed in Chinese)
' 整数: 42
' integer: 42
' 计算: 7 * 6 = 42
' arithmetic: 7 * 6 = 42
' 整数除法: 17 \ 5 = 3
' integer division: 17 \ 5 = 3
' 取余: 17 MOD 5 = 2
' remainder: 17 MOD 5 = 2
' 浮点(×100): 4.75 * 100 = 475
' float (x100): 4.75 * 100 = 475
' 循环求和: 1..10 = 55
' loop sum: 1..10 = 55
' 阶乘: 10! = 3628800
' factorial: 10! = 3628800
' === done ===
'
' ◆ 本前端的三条写法要求（都是实测出来的，不是风格偏好）
' ◆ Three syntax requirements of this frontend (all of them measured, not style preferences)
' ① `PRINT "…"; 值` —— **分号不加分隔符**，末尾自动补换行（见 whack.bas 的说明）。
' ① `PRINT "..."; value` -- **the semicolon adds no separator**, a newline is appended at the end (see the notes in whack.bas).
' ② 模块级变量必须在赋值前 `DIM`。
' ② Module-level variables must be `DIM`ed before they are assigned.
' ③ 整除用 `\`、取余用 `MOD`（QBasic 方言，`BasicDialect=qbasic`）。
' ③ Use `\` for integer division and `MOD` for the remainder (QBasic dialect, `BasicDialect=qbasic`).
'
' ◆ 本前端**浮点的三处已知缺陷** —— ✅ **三处都已修好（2026-10-04 复验）**（本文件当年刻意绕开）
' ◆ **Three known float defects** in this frontend — ✅ **all three fixed (re-checked 2026-10-04)** (this file deliberately avoided them back then)
' 当年在 `Examples/basic/demo_std.bas` 这条链上实测过，最小复现（下面是**当年的**记录）：
' They were measured back then on the `Examples/basic/demo_std.bas` chain; the minimal reproductions (the records below are from back then):
'
' DIM x AS SINGLE
' x = 4.75 : PRINT x * 100 ⇒ 0 （应 475 —— **浮点字面量赋给变量即丢值**）
' x = 4.75 : PRINT x * 100 => 0 (expected 475 -- **assigning a float literal to a variable loses the value**)
' PRINT 4.75 ⇒ 4 （**PRINT 浮点按整数截断**，值本身是对的）
' PRINT 4.75 => 4 (**PRINT truncates a float to an integer**; the value itself is correct)
' PRINT 10 / 4 ⇒ 2 （QBasic 的 `/` 是**浮点除**，应 2.5；
' PRINT 10 / 4 => 2 (QBasic's `/` is **float division**, expected 2.5;
' 只有 `\` 才是整除）
' only `\` is integer division)
'
' 第一条当年最要命：**浮点变量读回来恒为 0**（SINGLE / DOUBLE 都一样）。
' The first one hurt the most back then: **a float variable always read back as 0** (SINGLE and DOUBLE alike).
' 所以这里只演示"浮点字面量直接参与运算"这条路径 —— `4.75 * 100` 当年算出来确实是 475（值正确），
' So here we only demonstrate the "a float literal used directly in an expression" path -- back then `4.75 * 100` really did evaluate to 475 (the value was correct);
' 只是**不能存进变量、也不能直接 PRINT**。
' it just **could not be stored in a variable, and could not be PRINTed directly**.
'
' ✅ **2026-10-04 实测**：`DIM x AS SINGLE / x = 4.75 / PRINT x` → `4.75`、`PRINT x * 100` → `475`、
' ✅ **Measured on 2026-10-04**: `DIM x AS SINGLE / x = 4.75 / PRINT x` -> `4.75`, `PRINT x * 100` -> `475`,
' `DIM y AS DOUBLE / y = 2.5 / PRINT y` → `2.5`、`PRINT 10 / 4` → `2.5`、`PRINT 7 \ 2` → `3`；
' `DIM y AS DOUBLE / y = 2.5 / PRINT y` -> `2.5`, `PRINT 10 / 4` -> `2.5`, `PRINT 7 \ 2` -> `3`;
' **浮点变量读回来不再是 0**。⇒ 下面 ⑤ 只走字面量那条路径**是历史的写法**（能跑就别动），
' **a float variable no longer reads back as 0**. => item ⑤ below taking the literal path **is how it was written back then** (if it runs, leave it alone);
' 新写的代码可以正常用浮点变量。
' newly written code may use float variables normally.
' ── UI 接口：引用**库侧**的声明文件（原先这里是一屏 NATIVE 声明）────────────────
' ── UI interface: include the **library-side** declaration file (this used to be a screenful of NATIVE declarations)
'$INCLUDE: 'vml_ui.bas'
' ── 变量声明（必须在赋值之前）────────────────────────────────
' ── Variable declarations (must come before any assignment) ────────────────────────────────
DIM i AS INTEGER
DIM sum AS INTEGER
DIM fact AS INTEGER
DIM a AS INTEGER
DIM b AS INTEGER
DIM LANG AS INTEGER
' 界面语言：0 = 中文 / 1 = 英文（ui_scr_get_language 是 syscall，开局查一次）
' UI language: 0 = Chinese / 1 = English (ui_scr_get_language is a syscall, queried once at startup)
LANG = ui_scr_get_language()
IF LANG = 0 THEN PRINT "=== BASIC 标准输出 demo ===" ELSE PRINT "=== BASIC standard-output demo ==="
' ① 字符串字面量（含中文 —— 源码按 UTF-8 存，词法器直通）
' ① String literal (contains Chinese -- the source is stored as UTF-8 and the lexer passes it straight through)
IF LANG = 0 THEN PRINT "字符串: 你好，世界" ELSE PRINT "string: hello, world"
' ② 整数
' ② Integer
i = 42
IF LANG = 0 THEN PRINT "整数: "; i ELSE PRINT "integer: "; i
' ③ 整数运算
' ③ Integer arithmetic
a = 7
b = 6
IF LANG = 0 THEN PRINT "计算: 7 * 6 = "; a * b ELSE PRINT "arithmetic: 7 * 6 = "; a * b
' ④ 整除与取余（QBasic 方言：`\` = 整除，`MOD` = 取余）
' ④ Integer division and remainder (QBasic dialect: `\` = integer division, `MOD` = remainder)
IF LANG = 0 THEN PRINT "整数除法: 17 \ 5 = "; 17 \ 5 ELSE PRINT "integer division: 17 \ 5 = "; 17 \ 5
IF LANG = 0 THEN PRINT "取余: 17 MOD 5 = "; 17 MOD 5 ELSE PRINT "remainder: 17 MOD 5 = "; 17 MOD 5
' ⑤ 浮点：只走"字面量直接运算"这条路径（当年那三处缺陷只让这条能走通；
' ⑤ Float: only the "literal used directly in an expression" path (back then the three defects left only this one working;
' 该缺陷 2026-10-04 复验已修好，见文件头）
' that defect was re-checked fixed on 2026-10-04, see the top of the file)
IF LANG = 0 THEN PRINT "浮点(×100): 4.75 * 100 = "; 4.75 * 100 ELSE PRINT "float (x100): 4.75 * 100 = "; 4.75 * 100
' ⑥ 循环求和 1..10
' ⑥ Loop sum 1..10
sum = 0
FOR i = 1 TO 10
sum = sum + i
NEXT i
IF LANG = 0 THEN PRINT "循环求和: 1..10 = "; sum ELSE PRINT "loop sum: 1..10 = "; sum
' ⑦ 循环求阶乘 10!（3628800 —— 用整数足够，不必上浮点）
' ⑦ Loop factorial 10! (3628800 -- integers are enough, no need to go to floats)
fact = 1
FOR i = 1 TO 10
fact = fact * i
NEXT i
IF LANG = 0 THEN PRINT "阶乘: 10! = "; fact ELSE PRINT "factorial: 10! = "; fact
PRINT "=== done ==="