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OpCodes.Brfalse Field

Transfers control to a target instruction if value is false, a null reference (Nothing in Visual Basic), or zero.

[Visual Basic]
Public Shared ReadOnly Brfalse As OpCode
[C#]
public static readonly OpCode Brfalse;
[C++]
public: static OpCode Brfalse;
[JScript]
public static var Brfalse : OpCode;

Remarks

The following table lists the instruction's hexadecimal and Microsoft Intermediate Language (MSIL) assembly format, along with a brief reference summary:

Format Assembly Format Description
39 < int32 > brfalse target

brnull target

brzero target

Branches to a target instruction at the specified offset if false.

The stack transitional behavior, in sequential order, is:

  1. value is pushed onto the stack by a previous operation.
  2. value is popped from the stack; if value is false, branch to target.

The brfalse instruction (and its aliases brnull and brzero) transfers control to the specified target instruction if value (of type int32, int64, object reference O, managed pointer &, transient pointer *, natural int) is zero (false). If value is non-zero (true) execution continues at the next instruction.

The target instruction is represented as a 4-byte signed offset from the beginning of the instruction following the current instruction.

Control can only be transferred to the first of these prefixes if the target instruction has one or more prefix codes. Control transfers into and out of try, catch, filter, and finally blocks cannot be performed by this instruction.

The following Emit constructor overload can use the brfalse opcode:

  • ILGenerator.Emit(OpCode, Label)

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

OpCodes Class | OpCodes Members | System.Reflection.Emit Namespace

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