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const expect = @import("std").testing.expect;
test "for basics" {
const items = [_]i32{ 4, 5, 3, 4, 0 };
var sum: i32 = 0;
// For loops iterate over slices and arrays.
for (items) |value| {
// Break and continue are supported.
if (value == 0) {
continue;
}
sum += value;
}
try expect(sum == 16);
// To iterate over a portion of a slice, reslice.
for (items[0..1]) |value| {
sum += value;
}
try expect(sum == 20);
// To access the index of iteration, specify a second condition as well
// as a second capture value.
var sum2: i32 = 0;
for (items, 0..) |_, i| {
try expect(@TypeOf(i) == usize);
sum2 += @as(i32, @intCast(i));
}
try expect(sum2 == 10);
// To iterate over consecutive integers, use the range syntax.
// Unbounded range is always a compile error.
var sum3: usize = 0;
for (0..5) |i| {
sum3 += i;
}
try expect(sum3 == 10);
}
test "multi object for" {
const items = [_]usize{ 1, 2, 3 };
const items2 = [_]usize{ 4, 5, 6 };
var count: usize = 0;
// Iterate over multiple objects.
// All lengths must be equal at the start of the loop, otherwise detectable
// illegal behavior occurs.
for (items, items2) |i, j| {
count += i + j;
}
try expect(count == 21);
}
test "for reference" {
var items = [_]i32{ 3, 4, 2 };
// Iterate over the slice by reference by
// specifying that the capture value is a pointer.
for (&items) |*value| {
value.* += 1;
}
try expect(items[0] == 4);
try expect(items[1] == 5);
try expect(items[2] == 3);
}
test "for else" {
// For allows an else attached to it, the same as a while loop.
const items = [_]?i32{ 3, 4, null, 5 };
// For loops can also be used as expressions.
// Similar to while loops, when you break from a for loop, the else branch is not evaluated.
var sum: i32 = 0;
const result = for (items) |value| {
if (value != null) {
sum += value.?;
}
} else blk: {
try expect(sum == 12);
break :blk sum;
};
try expect(result == 12);
}
// test
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