Note: This article compares loops and recursion from the perspective of Go language.

When writing programs, we often encounter situations where a series of data or operations need to be processed repeatedly. To achieve this we need to use loops or recursion. Loops and recursions are both commonly used processing methods, but in practical applications, they each have advantages and disadvantages, so the actual situation needs to be considered when choosing which method to use. This article will conduct a comparative study of loops and recursion in the Go language.

1. Loop

Loop is a mechanism that repeatedly executes a certain section of code. There are three main loop methods in Go language: for loop, while loop and do...while loop.

1. for loop

The for loop is the most commonly used loop method in the Go language. It is very convenient to use for loop when the number of loops is known. There are two forms of for loops: one is for i := 0; i < n; i {}, and the other is for {}. The former is a situation where the number of loops is specified, and the number of loops can be controlled through the i variable, while the latter is an infinite loop, and the break statement can be called in the loop body to interrupt the loop.

Sample code:

// 計算1到n的整數(shù)和
func sum(n int) int {
    res := 0
    for i := 1; i <= n; i++ {
        res += i
    }
    return res
}

2. while loop

There is no while loop keyword in the Go language, but you can use a for loop to simulate a while loop. Just place the conditional expression outside the loop body.

Sample code:

// 求一個數(shù)的平方根，精度為eps
func sqrt(x float64, eps float64) float64 {
    z := x
    for z*z-x > eps {
        z = z - (z*z-x)/(2*z)
    }
    return z
}

3. do...while loop

There is no do...while loop keyword in Go language, but you can use for loop to Simulate do...while loop. Just put the loop body after the for loop.

Sample code:

// 打印出1到n的所有奇數(shù)
func odd(n int) {
    i := 1
    for {
        if i > n {
            break
        }
        fmt.Println(i)
        i += 2
    }
}

2. Recursion

Recursion is a function mechanism that calls itself. Functions in Go language can be called recursively, but you need to pay attention to controlling the recursion depth, otherwise it will cause stack overflow problems. During the recursive process, each recursion is required to be smaller than the previous recursion to ensure that the program does not fall into an infinite loop.

Sample code:

// 計算斐波那契數(shù)列的第n項
func fib(n int) int {
    if n == 1 || n == 2 {
        return 1
    }
    return fib(n-1) + fib(n-2)
}

3. Comparison of loops and recursion

Both loops and recursion can complete the function of repeatedly processing a series of data or operations, but they are different. There are pros and cons.

The advantage of looping is that it is highly efficient and can handle large-scale data. The disadvantage of loops is that the code is less readable and prone to problems such as infinite loops.

The advantage of recursion is that the code is concise and easy to understand and maintain. The disadvantage of recursion is that it is less efficient, because each recursion requires saving the context information of the function call to the stack. If the recursion depth is too deep, it may cause stack overflow problems.

In actual applications, you need to choose whether to use loops or recursions according to different needs. If the amount of data to be processed is large, or a large amount of calculations are required, loops should be used; if the problem to be processed is relatively simple, or more elegant code needs to be used, recursion can be used. At the same time, when using recursion, you need to pay attention to controlling the depth of recursion and perform appropriate optimization to avoid program problems.

In short, loops and recursions are common processing methods in programming. We need to choose which method to use based on the actual situation, and optimize the code appropriately to better complete the programming task.

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