C#中 double 变量如何 转换 string类型
我的this.dtty.text=double.parse("1.35").tostring这个常量会转了但是我实际要用的是变量转换该怎么办啊赶紧来帮帮我吧...
我的this.dtty.text = double.parse("1.35").tostring 这个常量会转了 但是我实际要用的是变量转换 该怎么办啊 赶紧来帮帮我吧
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bool System.Boolean (布尔型,其值为 true 或者 false)
char System.Char (字符型,占有两个字节,表示 1 个 Unicode 字符)
byte System.Byte (字节型,占 1 字节,表示 8 位正整数,范围 0 ~ 255)
sbyte System.SByte (带符号字节型,占 1 字节,表示 8 位整数,范围 -128 ~ 127)
ushort System.UInt16 (无符号短整型,占 2 字节,表示 16 位正整数,范围 0 ~ 65,535)
uint System.UInt32 (无符号整型,占 4 字节,表示 32 位正整数,范围 0 ~ 4,294,967,295)
ulong System.UInt64 (无符号长整型,占 8 字节,表示 64 位正整数,范围 0 ~ 大约 10 的 20 次方)
short System.Int16 (短整型,占 2 字节,表示 16 位整数,范围 -32,768 ~ 32,767)
int System.Int32 (整型,占 4 字节,表示 32 位整数,范围 -2,147,483,648 到 2,147,483,647)
long System.Int64 (长整型,占 8 字节,表示 64 位整数,范围大约 -(10 的 19) 次方到 10 的 19 次方)
float System.Single (单精度浮点型,占 4 个字节)
double System.Double (双精度浮点型,占 8 个字节)
代码如下:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace TypeTest
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
bool bo = true;
byte b = 9;
char c = 'a';
sbyte sb = 8;
short s = 8;
int i= 7;
uint u = 6;
long l = 5;
this.textBox1.Text = "typetest";
this.textBox1.AppendText("bool -> " + bo.GetType().FullName + ""n");
this.textBox1.AppendText("byte -> " + b.GetType().FullName + ""n");
this.textBox1.AppendText("char -> " + c.GetType().FullName + ""n");
this.textBox1.AppendText("sbyte -> " + sb.GetType().FullName + ""n");
this.textBox1.AppendText("short -> " +s.GetType().FullName + ""n");
this.textBox1.AppendText("int -> " + i.GetType().FullName + ""n");
this.textBox1.AppendText("uint -> " +u.GetType().FullName + ""n");
this.textBox1.AppendText("long -> " +l.GetType().FullName + ""n");
//其实类型就不写上,自己可以真接加上去!
}
}
}
结果可看到:
typetestbool -> System.Boolean
byte -> System.Byte
char -> System.Char
sbyte -> System.SByte
short -> System.Int16
int -> System.Int32
uint -> System.UInt32
long -> System.Int64
//
说明,以后所编的代码都是写在private void Form1_Load(object sender, EventArgs e)中的
2、Value Type间的转换。
bool bo = true;
byte b = 9;
char c = 'a';
sbyte sb = 8;
short s = 8;
int i = 7;
uint u = 6;
long l = 5;
this.textBox1.Text = "datatype";
this.textBox1.AppendText("bool bo=" + bo.ToString() + ""n");
this.textBox1.AppendText("byte b= " + b.ToString() + ""n");
this.textBox1.AppendText("char c= " + c.ToString() + ""n");
this.textBox1.AppendText("sbyte sb= " + sb.ToString() + ""n");
this.textBox1.AppendText("short s= " + s.ToString() + ""n");
this.textBox1.AppendText("int i= " + i.ToString() + ""n");
this.textBox1.AppendText("uint u=" + u.ToString() + ""n");
this.textBox1.AppendText("long l= " + l.ToString() + ""n");
此段代码并没有转换数据类型,只说明它们的类型公别还是System.bool型…System.long型。
追加一行:int g = 1;
short h = g;
this.textBox1.AppendText("h = " + h.ToString() + ""n");
结果编译报错:
G:"Projects"Visual C#"Convert"Form1.cs(118): 无法将类型“int”隐式转换为“short”
数据要进行强制转换。
如上例修改如下:
short g = 1;
byte h = (byte) g; // 将 short 型的 g 的值强制转换成byte型后再赋给变量 h
this.textBox1.AppendText("h = " + h.ToString() + ""n");
就可以了!
Short->byte
short g = 265; //265 = 255 + 10
byte h = (byte) g;
this.textBox1.AppendText("h = " + h.ToString() + ""n");
注意:溢出问题!
3、ASCII<->Unicode
char ch = 'a';
short ii = 65;
this.textBox1.Text = "";
this.textBox1.AppendText("The ASCII code of "'" + ch + ""' is: " + (short)ch + ""n");
this.textBox1.AppendText("ASCII is " + ii.ToString() + ", the char is: " + (char)ii + ""n");
char name1 = '屈';
char name2 = '志';
short name3 = 21195;
this.textBox1.AppendText("The Unicode of "'" + name1 + ""' is: " + (short)name1 + ""n");
this.textBox1.AppendText("The Unicode of "'" + name2 + ""' is: " + (short)name2+ ""n");
this.textBox1.AppendText("Unicode is " + name3.ToString() + ", the name3 is: " + (char)name3 + ""n");
它的运行结果是
The ASCII code of 'a' is: 97
ASCII is 65, the char is: A
The Unicode of '屈' is: 23624
The Unicode of '志' is: 24535
Unicode is 21195, the name3 is: 勋
4、int<->string
float f = 12.3f;
string str = "258";
this.textBox1.Text = "";
this.textBox1.AppendText("f = " + f.ToString() + ""n");//float->string
if (int.Parse(str) == 258) //string->int
{
this.textBox1.AppendText("str convert to int successfully.");
}
else
{
this.textBox1.AppendText("str convert to int failed.");
5、String<->char[]
string str = "quzhixun";
char[] chars = str.ToCharArray();//string->char[]
this.textBox1.Text = "";
this.textBox1.AppendText("Length of ""quzhixun"" is " + str.Length + ""n");
this.textBox1.AppendText("Length of char array is " + chars.Length + ""n");
this.textBox1.AppendText("char[2] = " + chars[2] + ""n");
char[] name = { 'q', 'u', 'z', 'h', 'i', 'x', 'u','n' };
string sname = new String(name);//char[]->string
this.textBox1.AppendText("sname = """ + sname + """"n");
6、String<->byte[]
string s = "hi,屈志勋";
byte[] b1 = System.Text.Encoding.Default.GetBytes(s);//sting->byte[],半个英文1个字节,汉字2 个字节。
byte[] b2 = System.Text.Encoding.Unicode.GetBytes(s); //sting->byte[],都是两个字节。
string t1 = "", t2 = "";
foreach (byte b in b1)
{
t1 += b.ToString("") + " ";
}
foreach (byte b in b2)
{
t2 += b.ToString("") + " ";
}
this.textBox1.Text = "";
this.textBox1.AppendText("b1.Length = " + b1.Length + ""n");
this.textBox1.AppendText(t1 + ""n");
this.textBox1.AppendText("b2.Length = " + b2.Length + ""n");
this.textBox1.AppendText(t2 + ""n");
//
byte[] b = { 65, 66, 67 };
string s = System.Text.Encoding.ASCII.GetString(b);//byte[]->string
this.textBox1.AppendText("The string is: " + s + ""n");
//
7、转换十六进制
int a = 159357;
this.textBox1.Text = "";
this.textBox1.AppendText("a(10) = " + a.ToString() + ""n");
this.textBox1.AppendText("a(16) = " + a.ToString("x6") + ""n");
this.textBox1.AppendText("a(16) = " + a.ToString("X6") + ""n");
8、DateTime<->long
double doubleDate = DateTime.Now.ToOADate();//按原来的double值输出,DateTime->long
DateTime theDate = DateTime.FromOADate(doubleDate);//从原来的的double值获得System.DateTime对象,long->DateTime
this.textBox1.Text = "";
this.textBox1.AppendText("Double value of now: " + doubleDate.ToString() + ""n");
this.textBox1.AppendText("DateTime from double value: " + theDate.ToString() + ""n");
//
9、form DateTime
DateTime now = DateTime.Now;
string format;
this.textBox1.Text = "";
format = """year"":yyyy,""month"":MM,""day"":dd HH:mm:ss";
this.textBox1.AppendText(format + ": " + now.ToString(format) + ""n");
format = "yy年M日d日";
this.textBox1.AppendText(format + ": " + now.ToString(format) + ""n");
char System.Char (字符型,占有两个字节,表示 1 个 Unicode 字符)
byte System.Byte (字节型,占 1 字节,表示 8 位正整数,范围 0 ~ 255)
sbyte System.SByte (带符号字节型,占 1 字节,表示 8 位整数,范围 -128 ~ 127)
ushort System.UInt16 (无符号短整型,占 2 字节,表示 16 位正整数,范围 0 ~ 65,535)
uint System.UInt32 (无符号整型,占 4 字节,表示 32 位正整数,范围 0 ~ 4,294,967,295)
ulong System.UInt64 (无符号长整型,占 8 字节,表示 64 位正整数,范围 0 ~ 大约 10 的 20 次方)
short System.Int16 (短整型,占 2 字节,表示 16 位整数,范围 -32,768 ~ 32,767)
int System.Int32 (整型,占 4 字节,表示 32 位整数,范围 -2,147,483,648 到 2,147,483,647)
long System.Int64 (长整型,占 8 字节,表示 64 位整数,范围大约 -(10 的 19) 次方到 10 的 19 次方)
float System.Single (单精度浮点型,占 4 个字节)
double System.Double (双精度浮点型,占 8 个字节)
代码如下:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace TypeTest
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
bool bo = true;
byte b = 9;
char c = 'a';
sbyte sb = 8;
short s = 8;
int i= 7;
uint u = 6;
long l = 5;
this.textBox1.Text = "typetest";
this.textBox1.AppendText("bool -> " + bo.GetType().FullName + ""n");
this.textBox1.AppendText("byte -> " + b.GetType().FullName + ""n");
this.textBox1.AppendText("char -> " + c.GetType().FullName + ""n");
this.textBox1.AppendText("sbyte -> " + sb.GetType().FullName + ""n");
this.textBox1.AppendText("short -> " +s.GetType().FullName + ""n");
this.textBox1.AppendText("int -> " + i.GetType().FullName + ""n");
this.textBox1.AppendText("uint -> " +u.GetType().FullName + ""n");
this.textBox1.AppendText("long -> " +l.GetType().FullName + ""n");
//其实类型就不写上,自己可以真接加上去!
}
}
}
结果可看到:
typetestbool -> System.Boolean
byte -> System.Byte
char -> System.Char
sbyte -> System.SByte
short -> System.Int16
int -> System.Int32
uint -> System.UInt32
long -> System.Int64
//
说明,以后所编的代码都是写在private void Form1_Load(object sender, EventArgs e)中的
2、Value Type间的转换。
bool bo = true;
byte b = 9;
char c = 'a';
sbyte sb = 8;
short s = 8;
int i = 7;
uint u = 6;
long l = 5;
this.textBox1.Text = "datatype";
this.textBox1.AppendText("bool bo=" + bo.ToString() + ""n");
this.textBox1.AppendText("byte b= " + b.ToString() + ""n");
this.textBox1.AppendText("char c= " + c.ToString() + ""n");
this.textBox1.AppendText("sbyte sb= " + sb.ToString() + ""n");
this.textBox1.AppendText("short s= " + s.ToString() + ""n");
this.textBox1.AppendText("int i= " + i.ToString() + ""n");
this.textBox1.AppendText("uint u=" + u.ToString() + ""n");
this.textBox1.AppendText("long l= " + l.ToString() + ""n");
此段代码并没有转换数据类型,只说明它们的类型公别还是System.bool型…System.long型。
追加一行:int g = 1;
short h = g;
this.textBox1.AppendText("h = " + h.ToString() + ""n");
结果编译报错:
G:"Projects"Visual C#"Convert"Form1.cs(118): 无法将类型“int”隐式转换为“short”
数据要进行强制转换。
如上例修改如下:
short g = 1;
byte h = (byte) g; // 将 short 型的 g 的值强制转换成byte型后再赋给变量 h
this.textBox1.AppendText("h = " + h.ToString() + ""n");
就可以了!
Short->byte
short g = 265; //265 = 255 + 10
byte h = (byte) g;
this.textBox1.AppendText("h = " + h.ToString() + ""n");
注意:溢出问题!
3、ASCII<->Unicode
char ch = 'a';
short ii = 65;
this.textBox1.Text = "";
this.textBox1.AppendText("The ASCII code of "'" + ch + ""' is: " + (short)ch + ""n");
this.textBox1.AppendText("ASCII is " + ii.ToString() + ", the char is: " + (char)ii + ""n");
char name1 = '屈';
char name2 = '志';
short name3 = 21195;
this.textBox1.AppendText("The Unicode of "'" + name1 + ""' is: " + (short)name1 + ""n");
this.textBox1.AppendText("The Unicode of "'" + name2 + ""' is: " + (short)name2+ ""n");
this.textBox1.AppendText("Unicode is " + name3.ToString() + ", the name3 is: " + (char)name3 + ""n");
它的运行结果是
The ASCII code of 'a' is: 97
ASCII is 65, the char is: A
The Unicode of '屈' is: 23624
The Unicode of '志' is: 24535
Unicode is 21195, the name3 is: 勋
4、int<->string
float f = 12.3f;
string str = "258";
this.textBox1.Text = "";
this.textBox1.AppendText("f = " + f.ToString() + ""n");//float->string
if (int.Parse(str) == 258) //string->int
{
this.textBox1.AppendText("str convert to int successfully.");
}
else
{
this.textBox1.AppendText("str convert to int failed.");
5、String<->char[]
string str = "quzhixun";
char[] chars = str.ToCharArray();//string->char[]
this.textBox1.Text = "";
this.textBox1.AppendText("Length of ""quzhixun"" is " + str.Length + ""n");
this.textBox1.AppendText("Length of char array is " + chars.Length + ""n");
this.textBox1.AppendText("char[2] = " + chars[2] + ""n");
char[] name = { 'q', 'u', 'z', 'h', 'i', 'x', 'u','n' };
string sname = new String(name);//char[]->string
this.textBox1.AppendText("sname = """ + sname + """"n");
6、String<->byte[]
string s = "hi,屈志勋";
byte[] b1 = System.Text.Encoding.Default.GetBytes(s);//sting->byte[],半个英文1个字节,汉字2 个字节。
byte[] b2 = System.Text.Encoding.Unicode.GetBytes(s); //sting->byte[],都是两个字节。
string t1 = "", t2 = "";
foreach (byte b in b1)
{
t1 += b.ToString("") + " ";
}
foreach (byte b in b2)
{
t2 += b.ToString("") + " ";
}
this.textBox1.Text = "";
this.textBox1.AppendText("b1.Length = " + b1.Length + ""n");
this.textBox1.AppendText(t1 + ""n");
this.textBox1.AppendText("b2.Length = " + b2.Length + ""n");
this.textBox1.AppendText(t2 + ""n");
//
byte[] b = { 65, 66, 67 };
string s = System.Text.Encoding.ASCII.GetString(b);//byte[]->string
this.textBox1.AppendText("The string is: " + s + ""n");
//
7、转换十六进制
int a = 159357;
this.textBox1.Text = "";
this.textBox1.AppendText("a(10) = " + a.ToString() + ""n");
this.textBox1.AppendText("a(16) = " + a.ToString("x6") + ""n");
this.textBox1.AppendText("a(16) = " + a.ToString("X6") + ""n");
8、DateTime<->long
double doubleDate = DateTime.Now.ToOADate();//按原来的double值输出,DateTime->long
DateTime theDate = DateTime.FromOADate(doubleDate);//从原来的的double值获得System.DateTime对象,long->DateTime
this.textBox1.Text = "";
this.textBox1.AppendText("Double value of now: " + doubleDate.ToString() + ""n");
this.textBox1.AppendText("DateTime from double value: " + theDate.ToString() + ""n");
//
9、form DateTime
DateTime now = DateTime.Now;
string format;
this.textBox1.Text = "";
format = """year"":yyyy,""month"":MM,""day"":dd HH:mm:ss";
this.textBox1.AppendText(format + ": " + now.ToString(format) + ""n");
format = "yy年M日d日";
this.textBox1.AppendText(format + ": " + now.ToString(format) + ""n");
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我也不太明白你的意思,是不是比如说
定义一个变量: double a=0;
然后给变量赋值: a=1.35;
把doubel类型的a转成string类型:this.dtty.text = doubel.parse(a).tostring();
其实a本身是doubel类型 可以直接this.dtty.text = a.tostring();就可以了
定义一个变量: double a=0;
然后给变量赋值: a=1.35;
把doubel类型的a转成string类型:this.dtty.text = doubel.parse(a).tostring();
其实a本身是doubel类型 可以直接this.dtty.text = a.tostring();就可以了
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double a=1.35;
string s=Convert.ToString(a);
this.dtty.text = s;
string s=Convert.ToString(a);
this.dtty.text = s;
追问
double a=1.35; 你的这个a 已经赋了常量值 相当于它是个常量啊 我的a 是个变量 值是靠算出来的
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不是很明白你是神马意思
定义a
double a;
给a赋值
转换a
string s=Convert.ToString(a);
this.dtty.text = double.parse(s).tostring
定义a
double a;
给a赋值
转换a
string s=Convert.ToString(a);
this.dtty.text = double.parse(s).tostring
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