CIL - Instruction set reference with examples

Pop a value from the evaluation stack into local variable number 0.

  // C#
  var str = "cat";
  
  // MSIL
  ldstr "cat"
  stloc.0
  

The compiler will use this form of stloc to write to the first 4 local variables.

Pop a value from the evaluation stack into local variable number [index].

  // C#
  ...
  var localVariableNumber10 = "hello10";
  ...
  var localVariableNumber256 = "hello256";
  
  // MSIL
  ldstr "hello10"
  stloc.s 0A
  
  ldstr "hello256"
  stloc 00 01
  

The compiler will use the short form to write to local variables numbered 4 through 255.
It will use the long form of stloc for all remaining local variables.