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range attribute

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The [range] attribute lets you specify a range of allowable values for arguments or fields whose values are set at run time. When used with a pipe type, the attribute specifies the allowable range for the count of elements in the pipe chunks.

[range(low-val,high-val)] type-specifier declarator

Parameters

low-val

The lowest allowable value that the parameter or field can hold.

high-val

The highest allowable value that the parameter or field can hold.

type-specifier

An integral type other than hyper or __int64, a type identifier to an integral type, an enum type, or a pipe type name.

declarator

A standard C declarator, such as an identifier.

Remarks

Use the [range] attribute to modify the meaning of sensitive parameters or fields, such as those used for size or length, with conformant or varying arrays; or whenever you want to check a parameter or field value against a range of valid values. The attribute is applicable to top-level parameters as well as lower-level parameters and fields. Adding the [range] attribute to a type does not change its wire format, thus does not affect backward compatibility.

The [range] attribute can also be used on conformant data such as buffers or arrays with a conformance attribute. The effect is to limit all conformance sizes for the conformant data to the specified range. If the conformant data is a multi-dimensional array, each array dimension is limited to the specified range.

Use of [range] on conformant data requires that the compilation target be –target NT60 or higher.

Note that you must use the /robust compiler option when you compile your IDL file in order to generate the stub code that will perform these checks. Without the /robust switch, the MIDL compiler ignores this attribute.

Examples

HRESULT Method1(
    [in, range(0,100)] ULONG m,
    [in, range(0,100)] ULONG n,
    [size_is(m,n)] ULONG **pplong);

void InPipe(
    [in, range(0, MAX_CHUNK) LONG_PIPE pipe_date);

See also

Interface Definition (IDL) File

arrays

first_is

last_is

length_is

max_is

/robust

size_is

switch_is