30秒学会 Golang 片段 – FindLast

Returns the value of the last element in the provided collection that satisfies the provided testing function.

Implement an appropriate function for each type.
Use a for loop to iterate over elements in the given collection, using f to determine if the element matches.
Return the value of the last matching element and nil if a value is found.
Use fmt.Errorf() to generate an appropriate error and return it alongsie a zero value for the type.

代码实现

import "fmt"

func FindLastInt(arr []int, f func(int) bool) (int, error) {
    for i := len(arr) - 1; i >= 0; i-- {
        if f(arr[i]) {
            return arr[i], nil
        }
    }
    return 0, fmt.Errorf("No matches found")
}
func FindLastFloat64(arr []float64, f func(float64) bool) (float64, error) {
    for i := len(arr) - 1; i >= 0; i-- {
        if f(arr[i]) {
            return arr[i], nil
        }
    }
    return 0.0, fmt.Errorf("No matches found")
}
func FindLastBool(arr []bool, f func(bool) bool) (bool, error) {
    for i := len(arr) - 1; i >= 0; i-- {
        if f(arr[i]) {
            return arr[i], nil
        }
    }
    return false, fmt.Errorf("No matches found")
}
func FindLastString(arr []string, f func(string) bool) (string, error) {
    for i := len(arr) - 1; i >= 0; i-- {
        if f(arr[i]) {
            return arr[i], nil
        }
    }
    return "", fmt.Errorf("No matches found")
}

使用样例

FindLastInt([]int{1, 1, 2}, func(x int) bool { return x%2 == 0 }) // 2 nil
FindLastFloat64([]float64{4.0, 6.0}, func(x float64) bool { return x%2.0 == 1.0 }) // 0.0 "No matches found"