Question

How vector capacity work in Rust

Answer 1

fn main() {
    let mut v = Vec::new();
    println!("A: {}", v.capacity()); 
    
    v.push('a'); // capacity automatically increased 
    
    println!("B: {}", v.capacity()); 
    
    v.push('b'); 
    v.push('c'); 
    v.push('d'); 
    
    println!("C: {}", v.capacity()); 
    
    v.push('e'); // capacity automatically increased // reallocation
    
    println!("D: {}", v.capacity()); 
}



/*
run:

A: 0
B: 4
C: 4
D: 8

*/

 

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