int.Parse()和Convert.Toint()之间的任何性能差异？

Question

将字符串转换为int.Parse()和Convert.ToInt32()之间的整数值有什么显着的优点吗？

string stringInt = "01234";

int iParse = int.Parse(stringInt);

int iConvert = Convert.ToInt32(stringInt);

我发现了一个问题,询问有关转换VS转换,但我认为这是不同的,对不对？

Answer 1

当传递一个字符串作为参数时,Convert.ToInt32在内部调用int.Parse.所以唯一的区别是额外的空检查.

这是.NET Reflector的代码

public static int ToInt32(string value)
{
    if (value == null)
    {
        return 0;
    }
    return int.Parse(value, CultureInfo.CurrentCulture);
}

Answer 2

物有所值:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int iterations = 1000000;
            string val = "01234";

            Console.Write("Run 1: int.Parse() ");
            DateTime start = DateTime.Now;
            DoParse(iterations, val);
            TimeSpan duration = DateTime.Now - start;
            Console.WriteLine("Duration: " + duration.TotalMilliseconds.ToString() + "ms");

            Console.Write("Run 1: Convert.ToInt32() ");
            start = DateTime.Now;
            DoConvert(iterations, val);
            duration = DateTime.Now - start;
            Console.WriteLine("Duration: " + duration.TotalMilliseconds.ToString() + "ms");

            Console.Write("Run 2: int.Parse() ");
            start = DateTime.Now;
            DoParse(iterations, val);
            duration = DateTime.Now - start;
            Console.WriteLine("Duration: " + duration.TotalMilliseconds.ToString() + "ms");

            Console.Write("Run 2: Convert.ToInt32() ");
            start = DateTime.Now;
            DoConvert(iterations, val);
            duration = DateTime.Now - start;
            Console.WriteLine("Duration: " + duration.TotalMilliseconds.ToString() + "ms");

            Console.Write("Run 3: int.Parse() ");
            start = DateTime.Now;
            DoParse(iterations, val);
            duration = DateTime.Now - start;
            Console.WriteLine("Duration: " + duration.TotalMilliseconds.ToString() + "ms");

            Console.Write("Run 3: Convert.ToInt32() ");
            start = DateTime.Now;
            DoConvert(iterations, val);
            duration = DateTime.Now - start;
            Console.WriteLine("Duration: " + duration.TotalMilliseconds.ToString() + "ms");

            Console.ReadKey();
        }

        static void DoParse(int iterations, string val)
        {
            int x;
            for (int i = 0; i < iterations; i++)
            {
                x = int.Parse(val);
            }
        }

        static void DoConvert(int iterations, string val)
        {
            int x;
            for (int i = 0; i < iterations; i++)
            {
                x = Convert.ToInt32(val);
            }
        }

    }
}

每个1,000,000次迭代的结果:

Run 1: int.Parse() Duration: 312.5ms
Run 1: Convert.ToInt32() Duration: 328.125ms
Run 2: int.Parse() Duration: 296.875ms
Run 2: Convert.ToInt32() Duration: 312.5ms
Run 3: int.Parse() Duration: 312.5ms
Run 3: Convert.ToInt32() Duration: 312.5ms