1 /*
2 * Copyright (c) 2023 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 //! test for extern "C"
17 #![allow(clippy::approx_constant)]
18 use std::os::raw::c_double;
19 use std::os::raw::c_int;
20
21 extern "C" {
abs(num: c_int) -> c_int22 fn abs(num: c_int) -> c_int;
sqrt(num: c_double) -> c_double23 fn sqrt(num: c_double) -> c_double;
pow(num: c_double, power: c_double) -> c_double24 fn pow(num: c_double, power: c_double) -> c_double;
25 }
26
27 /// fn main()
main()28 fn main() {
29 let x: i32 = -123;
30 println!("This is an example of calling a C library function from Rust:");
31 println!("The absolute value of {x} is: {}.", unsafe { abs(x) });
32 let n: f64 = 9.0;
33 let p: f64 = 3.0;
34 println!("The {n}th power of {p} is: {}.", unsafe { pow(n, p) });
35 let mut y: f64 = 64.0;
36 println!("The square root of {y} is: {}.", unsafe { sqrt(y) });
37 y = -3.14;
38 println!("The square root of {y} is: {}.", unsafe { sqrt(y) });
39 }
40