@stdlib/napi/argv-int32array/README.md

C APIs for creating Node-API native add-ons.

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# argv_int32array

> Convert a Node-API value to a signed 32-bit integer array.

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## Usage

```javascript
var headerDir = require( '@stdlib/napi/argv-int32array' );
```

#### headerDir

Absolute file path for the directory containing header files for C APIs.

```javascript
var dir = headerDir;
// returns <string>
```

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## Examples

```javascript
var headerDir = require( '@stdlib/napi/argv-int32array' );

console.log( headerDir );
// => <string>
```

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* * *

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## C APIs

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### Usage

```c
#include "stdlib/napi/argv_int32array.h"
```

#### stdlib_napi_argv_int32array( env, value, \*\*data, \*length, \*message, \*err )

Converts a Node-API value to a signed 32-bit integer array.

```c
#include "stdlib/napi/argv_int32array.h"
#include <node_api.h>
#include <stdint.h>

static napi_value addon( napi_env env, napi_callback_info info ) {
    napi_value value;

    // ...

    int32_t *X;
    int64_t len;
    napi_value err;
    napi_status status = stdlib_napi_argv_int32array( env, value, &X, &len, "Must be a typed array.", &err );
    assert( status == napi_ok );
    if ( err != NULL ) {
        assert( napi_throw( env, err ) == napi_ok );
        return NULL;
    }

    // ...
}
```

The function accepts the following arguments:

-   **env**: `[in] napi_env` environment under which the function is invoked.
-   **value**: `[in] napi_value` Node-API value.
-   **data**: `[out] int32_t**` pointer for returning a reference to the output array.
-   **length**: `[out] int64_t*` pointer for returning the number of array elements.
-   **message**: `[in] char*` error message.
-   **err**: `[out] napi_value*` pointer for storing a JavaScript error. If not provided a number, the function sets `err` with a JavaScript error; otherwise, `err` is set to `NULL`.

```c
napi_status stdlib_napi_argv_int32array( const napi_env env, const napi_value value, int32_t **data, int64_t *length, const char *message, napi_value *err );
```

The function returns a `napi_status` status code indicating success or failure (returns `napi_ok` if success).

#### STDLIB_NAPI_ARGV_INT32ARRAY( env, X, len, argv, index )

Macro for converting an add-on callback argument to a signed 32-bit integer array.

```c
#include "stdlib/napi/argv_int32array.h"
#include "stdlib/napi/argv.h"
#include <node_api.h>
#include <stdint.h>

static void fcn( const int32_t *X, const int64_t xlen, int32_t *Y, const int64_t ylen ) {
    int64_t len;
    int64_t i;

    if ( xlen > ylen ) {
        len = ylen;
    } else {
        len = xlen;
    }
    for ( i = 0; i < len; i++ ) {
        Y[ i ] = X[ i ];
    }
}

// ...

static napi_value addon( napi_env env, napi_callback_info info ) {
    // Retrieve add-on callback arguments:
    STDLIB_NAPI_ARGV( env, info, argv, argc, 2 );

    // Convert the first argument to a C type:
    STDLIB_NAPI_ARGV_INT32ARRAY( env, X, xlen, argv, 0 );

    // Convert the second argument to a C type:
    STDLIB_NAPI_ARGV_INT32ARRAY( env, Y, ylen, argv, 1 );

    // ...

    fcn( X, xlen, Y, ylen );
}
```

The macro expects the following arguments:

-   **env**: environment under which the callback is invoked.
-   **X**: output variable name for the array.
-   **len**: output variable name for the array length.
-   **argv**: name of the variable containing add-on callback arguments.
-   **index**: argument index.

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