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I'm trying to get the size of a string that esi holds the address of the first byte.

mov ebx, SIZEOF [esi]

Why won't this run? For an error it gives me error A2081: mi, for that line number.

Robert Campbell
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1 Answers1

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Why won't this run?

The syntax for SIZEOF is:

  SIZEOF variable | type

This only works at assembly-time, not at run-time. And it's not translated into code. So you can't use it anywhere you want.

An example: 

.data
string BYTE "Hello World", 0

.code
mov eax, SIZEOF string ;  the size will be translated into an immediate value

If you can't know in advance the length of that string, you need to call some function to get it.

JosEduSol
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