> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arkffi.hmbill.cn/llms.txt
> Use this file to discover all available pages before exploring further.

# Mixed Parameter Types

> Calling C functions with mixed int, double, and string parameters

C functions often accept parameters of different types. arkffi handles this by separating numeric and string arguments into two arrays.

## Signature Encoding

| Code | C Type                           |
| ---- | -------------------------------- |
| `i`  | `int32_t`, `int`, `bool`, `char` |
| `l`  | `int64_t`, `uint64_t`, `void*`   |
| `d`  | `double`, `float`                |
| `s`  | `const char*`                    |

For a function like:

```c theme={null}
double compute(int mode, double value, const char* name);
```

The type string is `"ids"` and the return type is `"d"`.

## Using `callMixed`

```typescript theme={null}
const h = ffi.load('libffi_target.so');

const result = ffi.callMixed(
  h, 'compute',
  'ids',       // arg types: int32, double, CString
  'd',         // return type: double
  [0, 4.0],    // numeric args
  ['square'],  // string args
);

ffi.close(h);
```

## Using `dlopen`

```typescript theme={null}
const lib = dlopen('libffi_target.so', {
  compute: {
    args: [FFIType.int32, FFIType.double, FFIType.CString],
    returns: FFIType.double,
  },
});

lib.symbols.compute(0, 4.0, 'square');
```

## Supported Signatures

| Signature | C Function                                    |
| --------- | --------------------------------------------- |
| `id`      | `double fn(int32_t, double)`                  |
| `di`      | `double fn(double, int32_t)`                  |
| `ids`     | `double fn(int32_t, double, const char*)`     |
| `sid`     | `double fn(const char*, int32_t, double)`     |
| `isd`     | `double fn(int32_t, const char*, double)`     |
| `iid`     | `double fn(int32_t, int32_t, double)`         |
| `idi`     | `double fn(int32_t, double, int32_t)`         |
| `idid`    | `double fn(int32_t, double, int32_t, double)` |
| `ss`      | `int32_t fn(const char*, const char*)`        |
| `s`       | `double fn(const char*)`                      |