For 和 Foreach 的比较

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C#代码：public int LoopTest() { int s=0; int[] array={2,3,4,5,6,7,8,9}; For(int k=0;k<=7;k++) { s+=array[k]; }

Foreach(int a in array) { s+=a; }

return s;

}

IL代码：.method public hidebysig instance int32 LoopTest() cil managed{ // 代码大小 78 (0x4e) .maxstack 3 .locals init ([0] int32 s, [1] int32[] 'array', [2] int32 k, [3] int32 a, [4] int32 CS$00000003$00000000, [5] int32[] CS$00000007$00000001, [6] int32 CS$00000008$00000002) IL_0000: ldc.i4.0 IL_0001: stloc.0 IL_0002: ldc.i4.8 IL_0003: newarr [mscorlib]System.Int32 IL_0008: dup IL_0009: ldtoken field valuetype '<PrivateImplementationDetails>'/'$$struct0x6000002-1' '<PrivateImplementationDetails>'::'$$method0x6000002-1' IL_000e: call void [mscorlib]System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(class [mscorlib]System.Array, valuetype [mscorlib]System.RuntimeFieldHandle) IL_0013: stloc.1 IL_0014: ldc.i4.0 IL_0015: stloc.2 IL_0016: br.s IL_0022 //For 开始的地方 IL_0018: ldloc.0 IL_0019: ldloc.1 IL_001a: ldloc.2 IL_001b: ldelem.i4 IL_001c: add IL_001d: stloc.0 IL_001e: ldloc.2 IL_001f: ldc.i4.1 IL_0020: add IL_0021: stloc.2 IL_0022: ldloc.2 IL_0023: ldc.i4.7 IL_0024: ble.s IL_0018 //For 结束的地方 IL_0026: ldloc.1 //Foreach 从这里开始 IL_0027: stloc.s CS$00000007$00000001 IL_0029: ldc.i4.0 IL_002a: stloc.s CS$00000008$00000002 IL_002c: br.s IL_003e IL_002e: ldloc.s CS$00000007$00000001 IL_0030: ldloc.s CS$00000008$00000002 IL_0032: ldelem.i4 IL_0033: stloc.3 IL_0034: ldloc.0 IL_0035: ldloc.3 IL_0036: add IL_0037: stloc.0 IL_0038: ldloc.s CS$00000008$00000002 IL_003a: ldc.i4.1 IL_003b: add IL_003c: stloc.s CS$00000008$00000002 IL_003e: ldloc.s CS$00000008$00000002 IL_0040: ldloc.s CS$00000007$00000001 IL_0042: ldlen IL_0043: conv.i4 IL_0044: blt.s IL_002e //Foreach结束的地方 IL_0046: ldloc.0 IL_0047: stloc.s CS$00000003$00000000 //此乃自动生成的一个变量，保存返回值，void时没有 IL_0049: br.s IL_004b IL_004b: ldloc.s CS$00000003$00000000 IL_004d: ret} // end of method Class1::LoopTest