int.Parse()和Convert.ToInt32()之间的主要区别是什么? 哪一个是首选
没有区别。 Convert.ToInt32()在内部调用int.Parse()
除了一件事Convert.ToInt32()当参数为空时返回0
否则两者的工作方式是一样的
If you've got a string, and you expect it to always be an integer (say, if some web service is handing you an integer in string format), you'd use Int32.Parse(). If you're collecting input from a user, you'd generally use Int32.TryParse(), since it allows you more fine-grained control over the situation when the user enters invalid input. Convert.ToInt32() takes an object as its argument. (See Chris S's answer for how it works) Convert.ToInt32() also does not throw ArgumentNullException when its argument is null the way Int32.Parse() does. That also means that Convert.ToInt32() is probably a wee bit slower than Int32.Parse(), though in practice, unless you're doing a very large number of iterations in a loop, you'll never notice it.
TryParse更快…
The first of these functions, Parse, is one that should be familiar to any .Net developer. This function will take a string and attempt to extract an integer out of it and then return the integer. If it runs into something that it can’t parse then it throws a FormatException or if the number is too large an OverflowException. Also, it can throw an ArgumentException if you pass it a null value. TryParse is a new addition to the new .Net 2.0 framework that addresses some issues with the original Parse function. The main difference is that exception handling is very slow, so if TryParse is unable to parse the string it does not throw an exception like Parse does. Instead, it returns a Boolean indicating if it was able to successfully parse a number. So you have to pass into TryParse both the string to be parsed and an Int32 out parameter to fill in. We will use the profiler to examine the speed difference between TryParse and Parse in both cases where the string can be correctly parsed and in cases where the string cannot be correctly parsed. The Convert class contains a series of functions to convert one base class into another. I believe that Convert.ToInt32(string) just checks for a null string (if the string is null it returns zero unlike the Parse) then just calls Int32.Parse(string). I’ll use the profiler to confirm this and to see if using Convert as opposed to Parse has any real effect on performance.
带有示例的源代码
希望这能有所帮助。
区别在于:
Int32.Parse()和Int32.TryParse()只能转换字符串。Convert.ToInt32()可以接受任何实现IConvertible的类。如果传递给它一个字符串，那么它们是等效的，除了类型比较等额外开销。如果要转换字符串，那么TryParse()可能是更好的选择。
请看反射镜:
int.Parse("32"):
public static int Parse(string s)
{
return System.Number.ParseInt32(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo);
}
这是一个调用:
internal static unsafe int ParseInt32(string s, NumberStyles style, NumberFormatInfo info)
{
byte* stackBuffer = stackalloc byte[1 * 0x72];
NumberBuffer number = new NumberBuffer(stackBuffer);
int num = 0;
StringToNumber(s, style, ref number, info, false);
if ((style & NumberStyles.AllowHexSpecifier) != NumberStyles.None)
{
if (!HexNumberToInt32(ref number, ref num))
{
throw new OverflowException(Environment.GetResourceString("Overflow_Int32"));
}
return num;
}
if (!NumberToInt32(ref number, ref num))
{
throw new OverflowException(Environment.GetResourceString("Overflow_Int32"));
}
return num;
}
Convert.ToInt32("32"):
public static int ToInt32(string value)
{
if (value == null)
{
return 0;
}
return int.Parse(value, CultureInfo.CurrentCulture);
}
正如第一个(Dave M的)评论所说。
Convert.ToInt32
有19种重载或者19种不同的调用方式。2010年的版本可能会更多。
它将尝试从以下类型进行转换;
对象，Boolean, Char, SByte, Byte, Int16, UInt16, Int32, UInt32, Int64, UInt64，单个，双精度，十进制，字符串，日期
它还有很多其他的方法;一种方法与数字基础有关，两种方法涉及系统。IFormatProvider
另一方面，Parse只有4种重载或者4种调用方法的不同方式。
Integer.Parse( s As String)
Integer.Parse( s As String, style As System.Globalization.NumberStyles )
Integer.Parse( s As String, provider As System.IFormatProvider )
Integer.Parse( s As String, style As System.Globalization.NumberStyles, provider As System.IFormatProvider )
为了澄清打开控制台应用程序，只需复制下面的代码并将其粘贴在静态void Main(string[] args)方法中，希望你能理解
public class Program
{
static void Main(string[] args)
{
int result;
bool status;
string s1 = "12345";
Console.WriteLine("input1:12345");
string s2 = "1234.45";
Console.WriteLine("input2:1234.45");
string s3 = null;
Console.WriteLine("input3:null");
string s4 = "1234567899012345677890123456789012345667890";
Console.WriteLine("input4:1234567899012345677890123456789012345667890");
string s5 = string.Empty;
Console.WriteLine("input5:String.Empty");
Console.WriteLine();
Console.WriteLine("--------Int.Parse Methods Outputs-------------");
try
{
result = int.Parse(s1);
Console.WriteLine("OutPut1:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut1:"+ee.Message);
}
try
{
result = int.Parse(s2);
Console.WriteLine("OutPut2:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut2:" + ee.Message);
}
try
{
result = int.Parse(s3);
Console.WriteLine("OutPut3:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut3:" + ee.Message);
}
try
{
result = int.Parse(s4);
Console.WriteLine("OutPut4:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut4:" + ee.Message);
}
try
{
result = int.Parse(s5);
Console.WriteLine("OutPut5:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut5:" + ee.Message);
}
Console.WriteLine();
Console.WriteLine("--------Convert.To.Int32 Method Outputs-------------");
try
{
result= Convert.ToInt32(s1);
Console.WriteLine("OutPut1:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut1:" + ee.Message);
}
try
{
result = Convert.ToInt32(s2);
Console.WriteLine("OutPut2:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut2:" + ee.Message);
}
try
{
result = Convert.ToInt32(s3);
Console.WriteLine("OutPut3:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut3:" + ee.Message);
}
try
{
result = Convert.ToInt32(s4);
Console.WriteLine("OutPut4:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut4:" + ee.Message);
}
try
{
result = Convert.ToInt32(s5);
Console.WriteLine("OutPut5:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut5:" + ee.Message);
}
Console.WriteLine();
Console.WriteLine("--------TryParse Methods Outputs-------------");
try
{
status = int.TryParse(s1, out result);
Console.WriteLine("OutPut1:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut1:" + ee.Message);
}
try
{
status = int.TryParse(s2, out result);
Console.WriteLine("OutPut2:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut2:" + ee.Message);
}
try
{
status = int.TryParse(s3, out result);
Console.WriteLine("OutPut3:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut3:" + ee.Message);
}
try
{
status = int.TryParse(s4, out result);
Console.WriteLine("OutPut4:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut4:" + ee.Message);
}
try
{
status = int.TryParse(s5, out result);
Console.WriteLine("OutPut5:" + result);
}
catch (Exception ee)
{
Console.WriteLine("OutPut5:" + ee.Message);
}
Console.Read();
}
}
这取决于参数类型。例如，我今天刚刚发现，它将使用ASCII值直接将char转换为int。这不是我想要的功能…
我警告过你!
public static int ToInt32(char value)
{
return (int)value;
}
Convert.ToInt32('1'); // Returns 49
int.Parse('1'); // Returns 1
Int32.parse(字符串)——>
Int32。Parse (string s)方法将数字的字符串表示形式转换为等效的32位有符号整数。当s是空引用时，它将抛出ArgumentNullException。如果s不是整数值，则抛出FormatException。当s表示一个小于MinValue或大于MaxValue的数字时，它将抛出OverflowException。例如:
string s1 = "1234";
string s2 = "1234.65";
string s3 = null;
string s4 = "123456789123456789123456789123456789123456789";
result = Int32.Parse(s1); //1234
result = Int32.Parse(s2); //FormatException
result = Int32.Parse(s3); //ArgumentNullException
result = Int32.Parse(s4); //OverflowException
Convert.ToInt32(字符串)——> 转换。ToInt32(string s)方法将指定的字符串表示形式转换为等效的32位有符号整数。这将依次调用Int32。Parse()方法。当s是空引用时，它将返回0而不是抛出ArgumentNullException。如果s不是整数值，则抛出FormatException。当s表示一个小于MinValue或大于MaxValue的数字时，它将抛出OverflowException。
例如:
result = Convert.ToInt32(s1); // 1234
result = Convert.ToInt32(s2); // FormatException
result = Convert.ToInt32(s3); // 0
result = Convert.ToInt32(s4); // OverflowException
int。Parse (string s)
RANGE >中的整数返回整数值 空值> argementnullexception 格式不是> FormatException 值不在RANGE > OverflowException
转换。ToInt32(字符串)
RANGE >中的整数返回整数值 空值>返回“0” 格式不是> FormatException 值不在RANGE > OverflowException
bool isParsed = int。TryParse（string s，out res）
RANGE中的整数>返回整数值，isParsed = true 空值>返回“0”，isParsed = false 不是格式>返回"0"，isParsed = false 值不在RANGE >返回"0"，isParsed = false
试试.....下面的代码
class Program
{
static void Main(string[] args)
{
string strInt = "24532";
string strNull = null;
string strWrongFrmt = "5.87";
string strAboveRange = "98765432123456";
int res;
try
{
// int.Parse() - TEST
res = int.Parse(strInt); // res = 24532
res = int.Parse(strNull); // System.ArgumentNullException
res = int.Parse(strWrongFrmt); // System.FormatException
res = int.Parse(strAboveRange); // System.OverflowException
// Convert.ToInt32(string s) - TEST
res = Convert.ToInt32(strInt); // res = 24532
res = Convert.ToInt32(strNull); // res = 0
res = Convert.ToInt32(strWrongFrmt); // System.FormatException
res = Convert.ToInt32(strAboveRange); //System.OverflowException
// int.TryParse(string s, out res) - Test
bool isParsed;
isParsed = int.TryParse(strInt, out res); // isParsed = true, res = 24532
isParsed = int.TryParse(strNull, out res); // isParsed = false, res = 0
isParsed = int.TryParse(strWrongFrmt, out res); // isParsed = false, res = 0
isParsed = int.TryParse(strAboveRange, out res); // isParsed = false, res = 0
}
catch(Exception e)
{
Console.WriteLine("Check this.\n" + e.Message);
}
}
这是int的一个细节。解析和转换。ToInt32: 比如说，你有一个char数组，char[] a=['1'，'2'，'3'，'4']，你想把每个元素转换成一个整数。 Convert.ToInt32([0])会给你一个数字49。它将其视为ASCII码 int.Parse(a[0])将为您提供正确的输出，即1
如果你有一个字符串数组string[] b=['1'，'2'，'3'，'4']，那么转换。ToInt32和int。Parse在输出上没有区别。两者都返回正确的整数。
Parse()方法提供了不能用于Convert()的数字样式。例如:
int i;
bool b = int.TryParse( "123-",
System.Globalization.NumberStyles.AllowTrailingSign,
System.Globalization.CultureInfo.InvariantCulture,
out i);
会解析带尾符号的数字，以便I == -123 尾随符号在ERP系统中很流行。
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