C# 检查 var 是否为 String 类型
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To check if var is String type
提问by Bulat Makhmutov
I have a problem in code in C#:
我在 C# 中的代码有问题：
I don't know how to implement logic - iterating through Hashtable having values of different data types, the schema I want is below:
我不知道如何实现逻辑 - 遍历具有不同数据类型值的 Hashtable，我想要的架构如下：
if the value in variable is String type
{
do action1;
}
else
{
do action2;
}
There is a hashtable containing data of Types - String and Int (combined):
有一个包含类型数据的哈希表 - String 和 Int（组合）：
public string SQLCondGenerator {
get
{
Hashtable conditions = new Hashtable();
//data having String data type
conditions.Add("miap", ViewState["miap_txt"]);
conditions.Add("pocode", ViewState["po_txt "]);
conditions.Add("materialdescription", ViewState["mat_desc_txt"]);
conditions.Add("suppliername", ViewState["supplier_txt"]);
conditions.Add("manufacturername", ViewState["manufacturer_txt"]);
//data having Int32 data type
conditions.Add("spareparts", ViewState["sp_id"]);
conditions.Add("firstfills", ViewState["ff_id"]);
conditions.Add("specialtools", ViewState["st_id"]);
conditions.Add("ps_deleted", ViewState["ps_del_id"]);
conditions.Add("po_manuallyinserted", ViewState["man_ins_id"]);
String SQLCondString = "";
String SQLCondStringConverted = "";
string s = string.Empty;
foreach (string name in conditions.Keys)
{
if (conditions[name] != null)
{
SQLCondString += name+ "=" +conditions[name]+ " and ";
Response.Write(conditions[name].GetType());
bool valtype = conditions[name].GetType().IsValueType;
if (valtype == string)
{
SQLCondString.Substring(0, SQLCondString.Length - 4);
SQLCondString += name + " and like '%" + conditions[name] + "%' and ";
}
}
}
//Response.Write("********************");
SQLCondStringConverted = SQLCondString.Substring(0, SQLCondString.Length - 4);
return SQLCondStringConverted;
}
}
May be I am wrong in coding, please advise!
可能是我编码有误，请指教！
Thanks!
谢谢！
采纳答案by Lee
if(conditions[name] is string)
{
}
else
{
}
回答by Candide
Hmm, I'm not sure why you are calling IsValueType, but this should be sufficient:
嗯，我不确定您为什么要调用IsValueType，但这应该足够了：
if (conditions[name] is string)
{
///
}
回答by Koko
Approach - 1
方法 - 1
Int32 Val = 0;
if (Int32.TryParse("Your Value", out Val))
{
//Your Logic for int
}
else
{
//Your Logic for String
}
Approach - 2 (using Late Binding)
方法 - 2（使用后期绑定）
Int32 Val = 0;
dynamic conditions = new Hashtable();
conditions.Add("miap", ViewState["miap_txt"]);
conditions.Add("pocode", ViewState["po_txt "]);
foreach (string name in conditions.Keys)
{
if (Int32.TryParse(conditions[name].ToString(), out Val))
{
//Your Logic for int
}
else
{
//Your Logic for String
}
}
回答by New_developer
I had the same issue but I was using textBoxes and needed to validate if the input is alphabets,-, or .
我遇到了同样的问题，但我使用的是文本框，需要验证输入是字母、- 还是 .
I generated a keypress event on my textBox and inserted the following method to check each keypress and give a prompt if its not a valid character:
我在我的文本框上生成了一个按键事件，并插入了以下方法来检查每个按键并在它不是有效字符时给出提示：
public static class Validator
{
public static bool IsNameString(TextBox tb, string name, KeyPressEventArgs e)
{
bool valid = true;
/* e.KeyChar contains the character that was pressed
e.Handled is a boolean that indicates that handling is done
if a bad character is entered, set e.Handled to true
*/
if (!char.IsLetter(e.KeyChar) && e.KeyChar != ' ' && e.KeyChar != '-' &&
e.KeyChar != '.' && e.KeyChar != (char)Keys.Back)
{
e.Handled = true;
valid = false;
MessageBox.Show(name+ " can only accept letters, space, - and .");
tb.Focus();
}
return valid;
}
}
usage:
用法：
private void txtCustomerName_KeyPress(object sender, KeyPressEventArgs e)
{
Validator.IsNameString(txtCustomerName, "Customer Name", e);
}
