Szathmáry László honlapja @ DEIK | Nim2 / break and continue

They exist in Nim and they work just like in Python/C.

However, when you have nested loops, you can break out of an outer loop (Java has this too).

Take this example:

for i in 1..3:
for j in 1..2:
echo &"{i} - {j}"

Output:

Say we want to stop the loops after "2 - 2". Here is how to do it:

block outer:
for i in 1..3:
for j in 1..2:
echo &"{i} - {j}"
if i == 2 and j == 2:
break outer
echo ""

A block can have a label, which is optional. Here we need that label.

Output:

The block keyword

The block keyword introduces a new scope.

block introduces a new scope
#include <stdio.h> int main() { int i = 2; // let's call it "the old i" printf("%d\n", i); // 2 { // new scope int i = 10; // new i variable printf("%d\n", i); // 10 // the new i dies at the end of the block } printf("%d\n", i); // 2, it's the old i return 0; }	let i = 2 echo i # 2 block: let i = 10 echo i # 10 echo i # 2

Comments are given in the C code (left side). The same thing happens in Nim.

Now the block has no label. It's an anonymous block.