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main.rs
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main.rs
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use std::time::Instant;
fn double(vec: &Vec<i32>) -> Vec<i32> {
let mut vec2 = Vec::new();
for x in vec.iter() {
vec2.push(x * 2);
}
return vec2;
}
fn double2(vec: &Vec<i32>) -> Vec<i32> {
let mut vec2 = Vec::with_capacity(vec.len());
for x in vec.iter() {
vec2.push(x * 2);
}
return vec2;
}
fn main() {
let mut vec = Vec::new();
for x in 0..100000 {
vec.push(x);
}
let mut total_time: u128 = 0;
{
for _ in 0..1000 {
let now = Instant::now();
double(&vec);
total_time += now.elapsed().as_micros();
}
println!("double: {}μs for 1000 times", total_time);
}
let mut total_time2: u128 = 0;
{
for _ in 0..1000 {
let now = Instant::now();
double2(&vec);
total_time2 += now.elapsed().as_micros();
}
println!("double2: {}μs for 1000 times", total_time2);
}
println!(
"double2 is {:.2} times faster than double",
total_time as f64 / total_time2 as f64
);
}