Does map guarantee the order of data reading?

In Go, the built-in map type does not guarantee the order of element traversal when reading. Iteration over a map occurs in a pseudo-random order, which may change with each program run. If a sorted traversal is needed, you should additionally store the keys in a slice and sort them before iteration.

Example of iterating over a map with sorted keys:

m := map[string]int{"b": 2, "a": 1, "c": 3}

// Get the keys
keys := make([]string, 0, len(m))
for k := range m {
    keys = append(keys, k)
}

// Sort the keys
sort.Strings(keys)

// Iterate over the sorted keys
for _, k := range keys {
    fmt.Println(k, m[k])
}