好吧，部分取决于的确切类型
list。它还取决于您使用的确切CLR。
它是否 有意义 ，将取决于您是否在循环中进行任何实际工作。在几乎 所有
情况下，对性能的影响都不是很大，但对可读性的影响则有利于
foreach循环。
我个人也会使用LINQ来避免出现“ if”：
foreach (var item in list.Where(condition)){}编辑：对于那些声称对
List<T>with进行迭代
foreach产生与
for循环相同代码的人来说，以下证据表明它不会：
static void IterateOverList(List<object> list){ foreach (object o in list) { Console.WriteLine(o); }}产生IL：
.method private hidebysig static void IterateOverList(class [mscorlib]System.Collections.Generic.List`1<object> list) cil managed{ // Code size 49 (0x31) .maxstack 1 .locals init (object V_0,valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<object> V_1) IL_0000: ldarg.0 IL_0001: callvirt instance valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<!0> class [mscorlib]System.Collections.Generic.List`1<object>::GetEnumerator() IL_0006: stloc.1 .try { IL_0007: br.s IL_0017 IL_0009: ldloca.s V_1 IL_000b: call instance !0 valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<object>::get_Current() IL_0010: stloc.0 IL_0011: ldloc.0 IL_0012: call void [mscorlib]System.Console::WriteLine(object) IL_0017: ldloca.s V_1 IL_0019: call instance bool valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<object>::MoveNext() IL_001e: brtrue.s IL_0009 IL_0020: leave.s IL_0030 } // end .try finally { IL_0022: ldloca.s V_1 IL_0024: constrained. valuetype [mscorlib]System.Collections.Generic.List`1/Enumerator<object> IL_002a: callvirt instance void [mscorlib]System.IDisposable::Dispose() IL_002f: endfinally } // end handler IL_0030: ret} // end of method Test::IterateOverList编译器对 数组的 处理方式不同，
foreach基本上将
for循环转换为循环，但不转换为
List<T>。这是数组的等效代码：
static void IterateOverArray(object[] array){ foreach (object o in array) { Console.WriteLine(o); }}// Compiles into....method private hidebysig static void IterateOverArray(object[] 'array') cil managed{ // Code size 27 (0x1b) .maxstack 2 .locals init (object V_0,object[] V_1,int32 V_2) IL_0000: ldarg.0 IL_0001: stloc.1 IL_0002: ldc.i4.0 IL_0003: stloc.2 IL_0004: br.s IL_0014 IL_0006: ldloc.1 IL_0007: ldloc.2 IL_0008: ldelem.ref IL_0009: stloc.0 IL_000a: ldloc.0 IL_000b: call void [mscorlib]System.Console::WriteLine(object) IL_0010: ldloc.2 IL_0011: ldc.i4.1 IL_0012: add IL_0013: stloc.2 IL_0014: ldloc.2 IL_0015: ldloc.1 IL_0016: ldlen IL_0017: conv.i4 IL_0018: blt.s IL_0006 IL_001a: ret} // end of method Test::IterateOverArray有趣的是，我在任何地方都找不到C＃3规范中记录的内容…
