Check speed of iterating with an index or the ranged value

slice_test.go

package main_test

import (
	"testing"
)

type Whatever struct {
	a, b, c int
}

func BenchmarkSliceRangeIteration(b *testing.B) {
	s := []Whatever{
		Whatever{1, 2, 3},
		Whatever{1, 2, 3},
		Whatever{1, 2, 3},
		Whatever{1, 2, 3},
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		for _, v := range s {
			a, b, c := v.a, v.b, v.c
			_, _, _ = a, b, c
		}
	}
}

func BenchmarkSliceIndexIteration(b *testing.B) {
	s := []Whatever{
		Whatever{1, 2, 3},
		Whatever{1, 2, 3},
		Whatever{1, 2, 3},
		Whatever{1, 2, 3},
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		for i := range s {
			a, b, c := s[i].a, s[i].b, s[i].c
			_, _, _ = a, b, c
		}
	}
}