diff --git a/string.vp b/string.vp
index 1df5953..2e34729 100644
--- a/string.vp
+++ b/string.vp
@@ -332,8 +332,8 @@ def atoll(src: str) -> t.CInt64T:
 # 含量级缩尺：|a| > 6.7e292 时先乘 2^-28 再算（否则 a*(2^27+1) 溢出为 inf）；
 # |a| 极小（< 1e-292）时先乘 2^28（否则 lo = a-hi 掉进次正规丢位）。
 # 缩尺因子均为 2 的幂 ⇒ 对正规数**无损**；调用方用 lo = a - hi 取下半部分。
-def _dd_split_hi(a: t.CDouble) -> t.CDouble:
-    aa: t.CDouble = a
+def _dd_split_hi(a: double) -> double:
+    aa: double = a
     big: int = 0
     small: int = 0
     if a > 6.7e292 or a < -6.7e292:
@@ -342,8 +342,8 @@ def _dd_split_hi(a: t.CDouble) -> t.CDouble:
     elif (a > 0.0 and a < 1.0e-292) or (a < 0.0 and a > -1.0e-292):
         aa = a * 268435456.0
         small = 1
-    tt: t.CDouble = aa * 134217729.0
-    hi: t.CDouble = tt - (tt - aa)
+    tt: double = aa * 134217729.0
+    hi: double = tt - (tt - aa)
     if big != 0:
         return hi * 268435456.0
     if small != 0:
@@ -352,56 +352,56 @@ def _dd_split_hi(a: t.CDouble) -> t.CDouble:
 
 
 # _dd_mul - 双 double 乘法：out = a × b（out[0]=hi, out[1]=lo）
-def _dd_mul(ah: t.CDouble, al: t.CDouble, bh: t.CDouble, bl: t.CDouble,
-            out: t.CArray[t.CDouble, 2]):
-    p: t.CDouble = ah * bh
-    a_hi: t.CDouble = _dd_split_hi(ah)
-    a_lo: t.CDouble = ah - a_hi
-    b_hi: t.CDouble = _dd_split_hi(bh)
-    b_lo: t.CDouble = bh - b_hi
-    e: t.CDouble = ((a_hi * b_hi - p) + a_hi * b_lo + a_lo * b_hi) + a_lo * b_lo
+def _dd_mul(ah: double, al: double, bh: double, bl: double,
+            out: t.CArray[double, 2]):
+    p: double = ah * bh
+    a_hi: double = _dd_split_hi(ah)
+    a_lo: double = ah - a_hi
+    b_hi: double = _dd_split_hi(bh)
+    b_lo: double = bh - b_hi
+    e: double = ((a_hi * b_hi - p) + a_hi * b_lo + a_lo * b_hi) + a_lo * b_lo
     e = e + (ah * bl + al * bh)
-    s: t.CDouble = p + e
+    s: double = p + e
     out[0] = s
     out[1] = e - (s - p)
 
 
 # _dd_add - 双 double 加法：out = a + b
-def _dd_add(ah: t.CDouble, al: t.CDouble, bh: t.CDouble, bl: t.CDouble,
-            out: t.CArray[t.CDouble, 2]):
-    s: t.CDouble = ah + bh
-    bb: t.CDouble = s - ah
-    e: t.CDouble = (ah - (s - bb)) + (bh - bb)
+def _dd_add(ah: double, al: double, bh: double, bl: double,
+            out: t.CArray[double, 2]):
+    s: double = ah + bh
+    bb: double = s - ah
+    e: double = (ah - (s - bb)) + (bh - bb)
     e = e + (al + bl)
-    r0: t.CDouble = s + e
+    r0: double = s + e
     out[0] = r0
     out[1] = e - (r0 - s)
 
 
 # _dd_div - 双 double 除法：out = a / b（q0 + 一步残差修正）
-def _dd_div(ah: t.CDouble, al: t.CDouble, bh: t.CDouble, bl: t.CDouble,
-            out: t.CArray[t.CDouble, 2], tmp: t.CArray[t.CDouble, 2]):
-    q0: t.CDouble = ah / bh
+def _dd_div(ah: double, al: double, bh: double, bl: double,
+            out: t.CArray[double, 2], tmp: t.CArray[double, 2]):
+    q0: double = ah / bh
     _dd_mul(bh, bl, q0, 0.0, tmp)
     _dd_add(ah, al, -tmp[0], -tmp[1], tmp)
-    q1: t.CDouble = tmp[0] / bh
+    q1: double = tmp[0] / bh
     _dd_add(q0, 0.0, q1, 0.0, out)
 
 
 # _dd_from_u64 - u64 → 双 double（精确：hi 为四舍五入值，lo 为精确残差）
-def _dd_from_u64(m: t.CUInt64T, out: t.CArray[t.CDouble, 2]):
-    hi: t.CDouble = t.CDouble(m)
-    lo: t.CDouble = 0.0
+def _dd_from_u64(m: t.CUInt64T, out: t.CArray[double, 2]):
+    hi: double = double(m)
+    lo: double = 0.0
     if m >= t.CUInt64T(9007199254740992):
-        lo = t.CDouble(m - t.CUInt64T(hi))
-    s: t.CDouble = hi + lo
-    bb: t.CDouble = s - hi
+        lo = double(m - t.CUInt64T(hi))
+    s: double = hi + lo
+    bb: double = s - hi
     out[0] = s
     out[1] = (hi - (s - bb)) + (lo - bb)
 
 
 # _dd_pow10 - 10^e 的双 double（e >= 0；按 ≤22 分块，每块可精确表示）
-def _dd_pow10(e: int, out: t.CArray[t.CDouble, 2], tmp: t.CArray[t.CDouble, 2]):
+def _dd_pow10(e: int, out: t.CArray[double, 2], tmp: t.CArray[double, 2]):
     out[0] = 1.0
     out[1] = 0.0
     k: int = e
@@ -409,7 +409,7 @@ def _dd_pow10(e: int, out: t.CArray[t.CDouble, 2], tmp: t.CArray[t.CDouble, 2]):
         step: int = 22
         if k < 22:
             step = k
-        p10: t.CDouble = 1.0
+        p10: double = 1.0
         i: int = 0
         while i < step:
             p10 = p10 * 10.0
@@ -421,8 +421,8 @@ def _dd_pow10(e: int, out: t.CArray[t.CDouble, 2], tmp: t.CArray[t.CDouble, 2]):
 
 
 # _pow2 - 2^n（|n| <= 1000）：循环乘 2/0.5，每步精确
-def _pow2(n: int) -> t.CDouble:
-    r: t.CDouble = 1.0
+def _pow2(n: int) -> double:
+    r: double = 1.0
     i: int = n
     if i >= 0:
         while i > 0:
@@ -436,8 +436,8 @@ def _pow2(n: int) -> t.CDouble:
 
 
 # _atof_scale_stepwise - 旧的逐步 ×/÷10 缩放（次正规/溢出场景的兜底）
-def _atof_scale_stepwise(x: t.CDouble, p: int) -> t.CDouble:
-    r: t.CDouble = x
+def _atof_scale_stepwise(x: double, p: int) -> double:
+    r: double = x
     e: int = p
     while e > 0:
         r = r * 10.0
@@ -448,14 +448,14 @@ def _atof_scale_stepwise(x: t.CDouble, p: int) -> t.CDouble:
     return r
 
 
-def atof(src: str) -> t.CDouble:
+def atof(src: str) -> double:
     s: str = src
     if s == None: return 0.0
     # 跳过空白
     while s[0] == ' ' or s[0] == '\t' or s[0] == '\n' or s[0] == '\r':
         s += 1
     # 符号
-    sign: t.CDouble = 1.0
+    sign: double = 1.0
     if s[0] == '-':
         sign = -1.0
         s += 1
@@ -523,14 +523,14 @@ def atof(src: str) -> t.CDouble:
         exp = exp * exp_sign
     p: int = dexp + exp
     if p == 0:
-        return sign * t.CDouble(mant)
+        return sign * double(mant)
     # 双 double 缩放：mant × 10^p，最后一次舍入
-    ta: t.CArray[t.CDouble, 2]
-    tb: t.CArray[t.CDouble, 2]
-    tc: t.CArray[t.CDouble, 2]
-    tr: t.CArray[t.CDouble, 2]
+    ta: t.CArray[double, 2]
+    tb: t.CArray[double, 2]
+    tc: t.CArray[double, 2]
+    tr: t.CArray[double, 2]
     _dd_from_u64(mant, ta)
-    v: t.CDouble = 0.0
+    v: double = 0.0
     if p > 0:
         _dd_pow10(p, tb, tr)
         _dd_mul(ta[0], ta[1], tb[0], tb[1], tr)
@@ -558,10 +558,10 @@ def atof(src: str) -> t.CDouble:
             and (v == 0.0 or v >= 2.2250738585072014e-308 or v <= -2.2250738585072014e-308):
         return sign * v
     # 溢出 / 次正规 / NaN → 回退旧逐步缩放（与旧实现语义一致）
-    return sign * _atof_scale_stepwise(t.CDouble(mant), p)
+    return sign * _atof_scale_stepwise(double(mant), p)
 
 
-def atof_out(src: str, out: t.CDouble | t.CPtr) -> int:
+def atof_out(src: str, out: double | t.CPtr) -> int:
     """atof 结果写入 out[0]（输出参数方式，避免跨模块 double 返回值传递 bug）
 
     返回值仅表示成功与否（1=成功，0=失败），结果值通过 out 指针传递，
@@ -569,7 +569,7 @@ def atof_out(src: str, out: t.CDouble | t.CPtr) -> int:
     """
     if out is None:
         return 0
-    v: t.CDouble = atof(src)
+    v: double = atof(src)
     out[0] = v
     return 1