使用 if 语句时，当前上下文中不存在该名称[重复]

我想用用户给出的小数位数来计算 Pi，当输入为 0 时，变量 piNumber 应设置为“3”而不是“3”，以便输出没有无用的逗号。

这有效

        static string PiNumberFinder(int amountOfDigits)
    {
        string piNumber = "3,";
        int dividedBy = 11080585;
        int divisor = 78256779;
        int result;
        for (int i = 0; i < amountOfDigits; i++)
        {
            if (dividedBy < divisor)
                dividedBy *= 10;

            result = dividedBy / divisor;

            string resultString = result.ToString();
            piNumber += resultString;

            dividedBy = dividedBy - divisor * result;
        }

        return piNumber;
    }

但如果使用 if 语句则不会

        static string PiNumberFinder(int amountOfDigits)
    {
        int dividedBy = 11080585;
        int divisor = 78256779;
        int result;
        if (amountOfDigits == 0)
        {
            string piNumber = "3";
        }
        else
        {
            string piNumber = "3,";
        }
        for (int i = 0; i < amountOfDigits; i++)
        {
            if (dividedBy < divisor)
                dividedBy *= 10;

            result = dividedBy / divisor;

            string resultString = result.ToString();
            piNumber += resultString;  // I get an error here

            dividedBy = dividedBy - divisor * result;
        }

        return piNumber;  // I get an error here
    }

对于上面代码中指向的行，我两次收到错误“名称 'piNumber' 在当前上下文中不存在”

您声明并赋值给piNumber内部变量if声明，因此它在此范围之外不可用。尝试先声明一下if

string piNumber;
if (amountOfDigits == 0)
{
    piNumber = "3";
}
else
{
    piNumber = "3,";
}