C# 如何将queryString值更改为（int）

可能重复：

如何将queryString值更改为（int）

换成这个

string str_id;
str_id = Request.QueryString["id"];
int id = Convert.ToInt32(str_id);

或者更简单更有效的方法

string str_id;
str_id = Request.QueryString["id"];
int id = int.Parse(str_id);

---

您必须使用

int.Parse（str\u id）

编辑：不信任用户输入

最好在解析之前检查输入是否为数字，因为此用法用于安全地获取

int

值：

int id;
string str_id = Request.QueryString["id"];
if(int.TryParse(str_id,out id))
{
    //id now contains your int value
}
else
{
    //str_id contained something else, i.e. not int
}

---

有几种方法可以做到这一点

string str_id = Request.QueryString["id"];

int id = 0;

//this prevent exception being thrown in case query string value is not a valid integer
Int32.TryParse(str_id, out id); //returns true if str_id is a valid integer and set the value of id to the value. False otherwise and id remains zero

其他

int id = Int32.Parse(str_id); //will throw exception if string is not valid integer
int id = Convert.ToInt32(str_id);  //will throw exception if string is not valid integer

---

+1对于

TryParse（）
string str_id = Request.QueryString["id"];

int id = 0;

//this prevent exception being thrown in case query string value is not a valid integer
Int32.TryParse(str_id, out id); //returns true if str_id is a valid integer and set the value of id to the value. False otherwise and id remains zero

int id = Int32.Parse(str_id); //will throw exception if string is not valid integer
int id = Convert.ToInt32(str_id);  //will throw exception if string is not valid integer