Question

How declare a vector with specific capacity to prevent reallocation in Rust

Answer 1

fn main() {
    let mut v = Vec::with_capacity(8);
    
    // no reallocation = work faster
    
    println!("A: {}", v.capacity()); 
    
    v.push('a'); 
    
    println!("B: {}", v.capacity()); 
    
    v.push('b'); 
    v.push('c'); 
    v.push('d'); 
    
    println!("C: {}", v.capacity()); 
    
    v.push('e'); 
    
    println!("D: {}", v.capacity()); 
}



/*
run:

A: 8
B: 8
C: 8
D: 8

*/

 

70+ SQL courses for beginners and professionals