Notes on details of recursive functions in Golang functions

In Golang, recursion is a way for a function to call itself. Many problems can be solved using recursive functions, such as calculating factorials, Fibonacci sequences, etc. However, when writing recursive functions, you need to pay attention to some details, otherwise program errors may occur. This article will introduce the details of recursive functions in Golang to help developers write more stable and reliable recursive functions.

1. Handling of basic situations

When writing a recursive function, you first need to consider the basic situation, that is, the conditions for the exit of the recursive function. If the base case is not handled correctly, a recursive function can call itself in an infinite loop, causing a stack overflow.

For example, here is the recursive function that computes factorial:

func Factorial(n int) int {

if n == 1 {
    return 1
}
return n * Factorial(n-1)

}

In the above example, The basic situation is that when n is equal to 1, 1 is returned. If there is no handling of the basic situation, the function will keep calling itself and cannot end.

2. Correct passing of parameters

In recursive functions, the passing of parameters is very important. If parameters are passed incorrectly, recursive functions may not return properly. Therefore, when designing a recursive function, you need to carefully consider the method and order of parameter passing.

For example, here is the recursive function that calculates the Fibonacci sequence:

func Fibonacci(n int) int {

if n == 0 {
    return 0
}
if n == 1 {
    return 1
}
return Fibonacci(n-1) + Fibonacci(n-2)

}

above In the example, parameter n represents the nth term of the Fibonacci sequence. When calling Fibonacci(n-1) and Fibonacci(n-2) recursively, the parameter n will continue to decrease until n equals 1 or 0. In this way, the recursive function can correctly return the nth term of the Fibonacci sequence.

3. Correct handling of return values

In recursive functions, return values ​​also need to be handled correctly. When calling recursively, a new stack frame is generated for each call until the base case is satisfied and the result is returned. In this process, the correct transmission of data and return values ​​between calls at all levels is required.

For example, the following is a recursive function that calculates the Fibonacci sequence, which uses a map as a cache:

var FibCache = map[int]int{}

func Fibonacci(n int) int {

if n == 0 {
    return 0
}
if n == 1 {
    return 1
}

if val, ok := FibCache[n]; ok {
    return val
}

val := Fibonacci(n-1) + Fibonacci(n-2)
FibCache[n] = val
return val

}

In the above example, using map as a cache can avoid repeated calculations. In a recursive call, if cached data already exists in the map, the cached result is returned directly to avoid repeated calculations.

Summary

When writing recursive functions, you need to pay attention to details such as basic situation processing, parameter passing, and return value processing. By handling these issues correctly, you can write stable and reliable recursive functions. At the same time, the efficiency of recursive functions also needs to be considered. In order to avoid stack overflow caused by excessive calls to recursive functions, tail recursion optimization, loop iteration, etc. can be considered.

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