# Keyword break

Expand description

Exit early from a loop or labelled block.

When `break` is encountered, execution of the associated loop body is immediately terminated.

``````let mut last = 0;

for x in 1..100 {
if x > 12 {
break;
}
last = x;
}

assert_eq!(last, 12);
println!("{last}");``````
Run

A break expression is normally associated with the innermost loop enclosing the `break` but a label can be used to specify which enclosing loop is affected.

``````'outer: for i in 1..=5 {
println!("outer iteration (i): {i}");

'_inner: for j in 1..=200 {
println!("    inner iteration (j): {j}");
if j >= 3 {
// breaks from inner loop, lets outer loop continue.
break;
}
if i >= 2 {
// breaks from outer loop, and directly to "Bye".
break 'outer;
}
}
}
println!("Bye.");``````
Run

When associated with `loop`, a break expression may be used to return a value from that loop. This is only valid with `loop` and not with any other type of loop. If no value is specified, `break;` returns `()`. Every `break` within a loop must return the same type.

``````let (mut a, mut b) = (1, 1);
let result = loop {
if b > 10 {
break b;
}
let c = a + b;
a = b;
b = c;
};
// first number in Fibonacci sequence over 10:
assert_eq!(result, 13);
println!("{result}");``````
Run

For more details consult the Reference on “break expression” and the Reference on “break and loop values”.