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# isSafeInteger

> Test if a finite [double-precision floating-point number][ieee754] is a safe integer.

<section class="usage">

## Usage

```javascript
var isSafeInteger = require( '@stdlib/math/base/assert/is-safe-integer' );
```

#### isSafeInteger( x )

Tests if a finite [double-precision floating-point number][ieee754] is a safe integer.

```javascript
var bool = isSafeInteger( 1.0 );
// returns true
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   An integer valued number is "safe" when the number can be exactly represented as a [double-precision floating-point number][ieee754]. For example,

    ```javascript
    var MAX_SAFE_INTEGER = require( '@stdlib/constants/float64/max-safe-integer' );
    // returns 9007199254740991

    var x = 9007199254740992;
    // returns 9007199254740992

    var y = 9007199254740993;
    // returns 9007199254740992

    var bool = ( x === y );
    // returns true
    ```

    In this example, `x` and `y` should be distinct, but they are not due to constraints imposed by storing numeric values in [double-precision floating-point format][ieee754]. "Safe" integers are thus [double-precision floating-point numbers][ieee754] having integer values with unequivocal binary representations.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var isSafeInteger = require( '@stdlib/math/base/assert/is-safe-integer' );

var bool = isSafeInteger( -5.0 );
// returns true

bool = isSafeInteger( 2.0e200 );
// returns false

bool = isSafeInteger( 3.14 );
// returns false

bool = isSafeInteger( NaN );
// returns false
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/math/base/assert/is_safe_integer.h"
```

#### stdlib_base_is_safe_integer( x )

Tests if a finite [double-precision floating-point number][ieee754] is a safe integer.

```c
#include <stdbool.h>

bool out = stdlib_base_is_safe_integer( 3.0 );
// returns true

out = stdlib_base_is_safe_integer( 2.0e200 );
// returns false
```

The function accepts the following arguments:

-   **x**: `[in] double` input value.

```c
bool stdlib_base_is_safe_integer( const double x );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/math/base/assert/is_safe_integer.h"
#include <stdio.h>
#include <stdbool.h>

int main( void ) {
    const double x[] = { 5.0, -5.0, 3.14, -3.14, 0.0, 0.0/0.0 };

    bool b;
    int i;
    for ( i = 0; i < 6; i++ ) {
        b = stdlib_base_is_safe_integer( x[ i ] );
        printf( "Value: %lf. Is safe integer? %s.\n", x[ i ], ( b ) ? "True" : "False" );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985

</section>

<!-- /.links -->
