C++98 Mapping for Built-In Types

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Mapping of Slice Built-In Types to C++ Types

The Slice built-in types are mapped to C++ types as shown in this table:

Slice

C++

bool

bool

byte

Ice::Byte

short

Ice::Short

int

Ice::Int

long

Ice::Long

float

Ice::Float

double

Ice::Double

string

std::string

Ice::Byte is a typedef for unsigned char. This guarantees that byte values are always in the range 0..255.

 All the basic types are guaranteed to be distinct C++ types, that is, you can safely overload functions that differ in only the types listed in the table above.

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Alternative String Mapping for C++

You can use a metadata directive, "cpp:type:wstring", to map strings to C++ std::wstring. For containers (such as interfaces or structures), the metadata directive applies to all strings within the container. A corresponding metadata directive, "cpp:type:string", can be used to selectively override the mapping defined by the enclosing container. For example:

Slice
["cpp:type:wstring"]
struct S1
{
    string x;                        // Maps to std::wstring
    ["cpp:type:wstring"] string y;   // Maps to std::wstring
    ["cpp:type:string"] string z;    // Maps to std::string
}

struct S2
{
    string x;                        // Maps to std::string
    ["cpp:type:string"] string y;    // Maps to std::string
    ["cpp:type:wstring"] string z;   // Maps to std::wstring
}

With these metadata directives, the strings are mapped as indicated by the comments. By default, narrow strings are encoded as UTF-8, and wide strings use a UTF encoding that is appropriate for the platform on which the application executes. You can override the encoding for narrow and wide strings by registering a string converter with the Ice run time.

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String View Mapping in C++

You can use the metadata directive cpp:view-type:string-view-type to map some string parameters to a custom C++ "view-type" of your choice. This view-type can reference memory without owning it, like the experimental string_view type. For example:

Slice
void sendString(["cpp:view-type:std::experimental::string_view"] string data);

maps to:

C++
// Proxy function for synchronous call: input parameter mapped to string_view type.
void sendString(const std::experimental::string_view&);

See Customizing the C++98 Mapping for a detailed description of the cpp:view-type metadata directive.

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See Also