如果在伊利诺伊州看起来像什么?

这里有一些 if 陈述及其如何翻译成IL:

ldc.i4.s 0x2f                      var i = 47;
stloc.0 

ldloc.0                            if (i == 47)
ldc.i4.s 0x2f
bne.un.s L_0012

ldstr "forty-seven!"                   Console.WriteLine("forty-seven!");
call Console::WriteLine

L_0012:
ldloc.0                            if (i > 0)
ldc.i4.0 
ble.s L_0020

ldstr "greater than zero!"             Console.WriteLine("greater than zero!");
call Console::WriteLine

L_0020:
ldloc.0                            bool b = (i != 0);
ldc.i4.0 
ceq 
ldc.i4.0 
ceq 
stloc.1 

ldloc.1                            if (b)
brfalse.s L_0035

ldstr "boolean true!"                  Console.WriteLine("boolean true!");
call Console::WriteLine

L_0035:
ret

这里需要注意的一点是:IL指令总是相反的。 if (i > 0) i <= 0 ,然后跳过 阻止。

使用的分支指令将根据堆栈顶部的值跳转到目标指令。

brfalse Branch to target if value is zero (false)
brtrue  Branch to target if value is non-zero (true)
beq     Branch to target if equal
bge     Branch to target if greater than or equal to
bgt     Branch to target if greater than
ble     Branch to target if less than or equal to
blt     Branch to target if less than
bne.un  Branch to target if unequal or unordered

if . 例如,如果您正在对照 null 编译器将发出 brfalse 指令(或a) brtrue

这个 如果 ILDASM 或者反射器是更好的学习工具。

一个简单的例子:

ldloc.1                    // loads first local variable to stack
ldc.i4.0                   // loads constant 0 to stack
beq                        // branch if equal

这等于

if(i == 0) //if i is the first local variable

有一篇关于 codeproject 关于这个。