10 Common Go Pitfalls Every PHP Developer Should Avoid

As a PHP developer with five years of experience, I have gradually shifted new projects from PHP to Go. During this transition I encountered several common pitfalls, which I summarize here.

1. Function Definition

Problem: The opening brace is placed on a new line, which is invalid in Go.

func main()
{
    fmt.Println("php是世界上最好的语言")
}

Solution: The brace must be on the same line as the function name.

func main() {
    fmt.Println("php是世界上最好的语言")
}

2. Map Definition and Initialization

Problem: Declaring a map without allocating memory causes a panic.

func main() {
    var m map[string]string
    m["php"] = "世界上最好的语言"
    m["go"]  = "世界上最好的语言"
    fmt.Println(m)
}

Solution: Use make to allocate the map before use.

func main() {
    m := make(map[string]string, 2)
    m["php"] = "世界上最好的语言"
    m["go"]  = "世界上最好的语言"
    fmt.Println(m)
}

3. JSON Marshalling

Problem: Struct fields are lowercase, making them unexported and resulting in empty JSON output.

type Student struct {
    id    int
    name  string
    score int
}

func main() {
    s := Student{1, "小明", 99}
    jsonS, _ := json.Marshal(s)
    fmt.Println(string(jsonS))
}

Solution: Export fields by capitalizing their names.

type Student struct {
    Id    int
    Name  string
    Score int
}

func main() {
    s := Student{1, "小明", 99}
    jsonS, _ := json.Marshal(s)
    fmt.Println(string(jsonS))
}

4. Modifying Elements Inside a Loop

Problem: Updating the loop variable does not change the original slice.

func main() {
    data := []int{1, 2, 3}
    for _, value := range data {
        value += 1
    }
    fmt.Println(data)
}

Solution: Use the index to modify the slice directly.

func main() {
    data := []int{1, 2, 3}
    for i := range data {
        data[i] += 1
    }
    fmt.Println(data)
}

5. Array vs. Slice Differences

Problem: Passing an array to a function results in value‑copy, so modifications are not reflected.

func change(data [2]int) {
    data[0] = 4
}

func main() {
    data := [2]int{1, 2}
    change(data)
    fmt.Println(data)
}

Solution: Use a slice, which shares the underlying array.

func change(data []int) {
    data[0] = 4
}

func main() {
    data := []int{1, 2}
    change(data)
    fmt.Println(data)
}

6. := Declaration and Variable Scope

Problem: Re‑declaring a variable with := inside an if block creates a new variable, leaving the outer one unchanged.

func main() {
    flag := 1
    if true {
        flag := 2
        flag++
    }
    fmt.Println(flag)
}

Solution: Use assignment ( =) to modify the existing variable.

func main() {
    flag := 1
    if true {
        flag = 2
        flag++
    }
    fmt.Println(flag)
}

Summary: These are some of the most common beginner pitfalls when moving from PHP to Go, covering syntax, data structures, JSON handling, loop semantics, and variable scope. Understanding and avoiding them can greatly smooth the learning curve.