Go语言中+Inf结果：解决金融计算中的变量初始化陷阱

package main

import (
    "fmt"
    "math"
)

var (
    interest,
    futureValue,
    period,
    presentValue float64
)

// 错误：ratex 在 interest 获得用户输入前被初始化
var ratex float64 = 1 + interest // interest 在此处为零值

func main() {
    numPeriod()
}

func numPeriod() {
    fmt.Println("Enter interest amount: ")
    fmt.Scanf("%g", &interest) // interest 在此处才获得实际值
    fmt.Println("Enter present value: ")
    fmt.Scanf("%g", &presentValue)
    fmt.Println("Enter future value: ")
    fmt.Scanf("%g", &futureValue)

    var logfvpvFactor float64 = futureValue / presentValue
    // 错误：logi 基于错误的 ratex 值计算
    var logi float64 = math.Log(ratex) // 由于 ratex 为 1，math.Log(1) 返回 0
    var logfvpv float64 = math.Log(logfvpvFactor)

    period = logfvpv / logi // 导致除以零，结果为 +Inf
    fmt.Printf("Number of period/s is = %g\n", period)
}

package main

import (
    "fmt"
    "math"
)

var (
    interest,
    futureValue,
    period,
    presentValue float64
)

func main() {
    numPeriod()
}

func numPeriod() {
    fmt.Println("Enter interest amount (e.g., 5 for 5%): ")
    fmt.Scanf("%g", &interest)
    fmt.Println("Enter present value: ")
    fmt.Scanf("%g", &presentValue)
    fmt.Println("Enter future value: ")
    fmt.Scanf("%g", &futureValue)

    // 修正：在 interest 获得用户输入后，再计算 rate 和 ratex
    var rate float64 = interest / 100 // 将百分比利率转换为小数
    var ratex float64 = 1 + rate      // (1 + i)

    // 确保 ratex 不为 1，即 rate 不为 0，以避免 math.Log(1) 产生 0
    if ratex == 1.0 {
        fmt.Println("Error: Interest rate cannot be zero for this calculation (log(1+i) would be zero).")
        return // 或者采取其他错误处理措施
    }

    var logfvpvFactor float64 = futureValue / presentValue
    var logi float64 = math.Log(ratex)
    var logfvpv float64 = math.Log(logfvpvFactor)

    // 检查 logi 是否为零，防止除以零
    if logi == 0.0 {
        fmt.Println("Error: The logarithm of (1 + interest rate) resulted in zero. This usually means the effective interest rate is zero.")
        return
    }

    period = logfvpv / logi
    fmt.Printf("Number of period/s is = %g\n", period)
}