我知道这很可能是一个愚蠢的问题,但我是一名大学生,他是C#和面向对象编程的新手.我试图在别处找到答案,但我找不到任何有用的东西.调试器一直告诉我变量’cust_num在当前上下文中不存在’.如果有人能告诉我我做错了什么并让我觉得自己像个白痴,我会非常感激.谢谢！
string get_cust_num()
{
bool cust_num_valid = false;
while (!cust_num_valid)
{
cust_num_valid = true;
Console.Write("Please enter customer number: ");
string cust_num = Console.ReadLine();
if (cust_num == "000000" || !Regex.IsMatch(cust_num,@"^[0-9]+$") || cust_num.Length != 6)
{
cust_num_valid = false;
Console.WriteLine("Invalid customer number detected. Customer numbers must be a 6 digit positive integer (zeros will not work)");
}
}
return cust_num;
}
解决方法
C#中的每个变量都存在于由花括号定义的范围内：
{
...
int x = 0;
...
x = x + 1; // <- legal
...
// <- x is defined up to here
}
x = x - 1; // <- illegal,providing there's no other "x" declared
在您的情况下,cust_num受到{…}的限制.如果cust_num_valid = true并且没有,那么它必须考虑代码应该返回什么值
cust_num.
while (!cust_num_valid)
{ // <- Scope of cust_num begins
cust_num_valid = true;
Console.Write("Please enter customer number: ");
string cust_num = Console.ReadLine();
if (cust_num == "000000" || !Regex.IsMatch(cust_num,@"^[0-9]+$") || cust_num.Length != 6)
{
cust_num_valid = false;
Console.WriteLine("Invalid customer number detected. Customer numbers must be a 6 digit positive integer (zeros will not work)");
}
} // <- Scope of cust_num ends
return cust_num; // <- out of scope
修复你的代码put string cust_num =“”;在外面：
string cust_num = ""; // <- declaration
while (!cust_num_valid)
{
cust_num_valid = true;
Console.Write("Please enter customer number: ");
cust_num = Console.ReadLine(); // <- no new declaration: "string" is removed
if (cust_num == "000000" || !Regex.IsMatch(cust_num,@"^[0-9]+$") || cust_num.Length != 6)
{
cust_num_valid = false;
Console.WriteLine("Invalid customer number detected. Customer numbers must be a 6 digit positive integer (zeros will not work)");
}
}
return cust_num;
