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OpCodes.Brfalse Field

Microsoft Silverlight will reach end of support after October 2021. Learn more.

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

Namespace:  System.Reflection.Emit
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Shared ReadOnly Brfalse As OpCode
public static readonly OpCode Brfalse

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 *, native 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 method overload can use the brfalse opcode:

  • ILGenerator.Emit(OpCode, Label)

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.