json error: Use of overloaded operator [] is ambiguous错误的解决方

// Note:
//int x = a[0].GetInt();     // Error: operator[ is ambiguous, as 0 also mean a null pointer of const char* type.
int y = a[SizeType(0)].GetInt(); // Cast to SizeType will work.
int z = a[0u].GetInt();     // This works too.

0u = 
SizeType(0)

Use of overloaded operator [] is ambiguous (with operand types 'const Json:Value' and 'int' )
  void Parse(constJson::Value &jsonObject) {
   rmb = jsonObject[0].asDouble();
  }

rmb = jsonObject[0U].asDouble();

rmb = jsonObject[SizeType(0)].asDouble();