第四章 C# .Parse（）int.TryParse Convert类型转换 ToString() 算数运算符关系运算符

原创已于 2024-04-20 15:02:47 修改 · 570 阅读

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#c# #开发语言

于 2023-07-25 21:25:03 首次发布

本文介绍了C#中将字符串转换为各种数值类型的方法，如Parse、TryParse和Convert类，同时展示了算术运算符的用法和关系运算符的示例。还提到了数据类型的大小以及如何判断数据类型。

一.Parse（）适用于string转换成值类型

         string strNumber = "123";
            int intNumber4= int.Parse(strNumber);
            Console.WriteLine(intNumber4);
            long longNumber4 =long.Parse(strNumber);
            Console.WriteLine(longNumber4);
            byte byteNumber  =byte.Parse(strNumber);
            Console.WriteLine(byteNumber);
            uint uintNumber =uint.Parse(strNumber);
            Console.WriteLine(uintNumber);
            float floatNumber4  = float.Parse(strNumber);
            Console.WriteLine(floatNumber4);
            // 注意bool类型转换
            string stringNumber5 = "true";
            bool boolNumber = bool.Parse(stringNumber5);
            Console.WriteLine(boolNumber);

1. int.TryParse

int.TryParse与 int.Parse 又较为类似，但它不会产生异常，转换成功返回 true，
转换失败返回 false。最后一个参数为输出值，如果转换失败，输出值为 0

     //尝试转换数据  如果不成功 会返回false结果 
            //成功返回 true
            int ab; //用于输出参数
            string stringNumber6 = "a12";
            bool isSuccess =  int.TryParse(stringNumber6, out ab);
            string  isSuccessStr = isSuccess?"转换成功":"转换失败";
            Console.WriteLine(isSuccessStr);
            Console.WriteLine(ab); // 转换失败结果为 0

2.Convert类型转换

适合各种类型相互转换

            //万能类型转换  任意类型之间转换 但是转换的内容要符合转换后类型的标准
            //否则抛出异常
            string stringNumber7 = "123";
            int intNumber7 = Convert.ToInt32(stringNumber7);
            long longNumber7 =Convert.ToInt64 (stringNumber7);
            short shortNumber7 = Convert.ToInt16 (stringNumber7);
            uint uintNumber7 = Convert.ToUInt32 (stringNumber7);
            ulong ulongNumber7 = Convert.ToUInt64 (stringNumber7);
            ushort ushortNumber7 = Convert.ToUInt16 (stringNumber7);
            float floatNumber7 = Convert.ToSingle(stringNumber7);
            double doubleNumber7 = Convert.ToDouble(stringNumber7);
            //bool类型转换成数字类型 时 对应的是 0 和1
            bool boolNumber7 = true;
            int intNumber8 = Convert.ToInt32(boolNumber7);
            Console.WriteLine(intNumber8);
 
 
           //这种情况就无法转换
            string s1 = "123abc";
            int a1 = Convert.ToInt32(s);
            double b1 = Convert.ToDouble(s);

3.ToString()

适合其他类型转换成字符串.

  //其他类型转换成字符串类型 方式1
            int intNumber9 = 100;
            Console.WriteLine(Convert.ToString(intNumber9));
            //其他类型转换成字符串类型 方式2
            string strNumber9 = intNumber9.ToString();
            Console.WriteLine(strNumber9);

4.算数运算符

+ - * / % ++ --

  //算术运算符  
            // +  -  *  /  %数字类型大类型和小类型结合 结果默认为大类型结果
            int intNumber = 10;
            int intNumber1 = 40;
            long longNumber = 20;
            //默认类型int
            int intNumber3 = intNumber + intNumber1;
            //隐式类型转换
            long longNumber3 = intNumber + intNumber1;
            //显示类型转换
            int intNumber4 = (int)(intNumber + longNumber);
 
            int intNumber5 = 100;
            float floatNumber = 10f;
            //字符串类型和字符串类型相加  拼接
            string stringNumber = "123";
            string stringNumber1 = "abc";
            string stringNumber2 = stringNumber + stringNumber1;
 
            //字符串类型和数字类型相加 拼接
            string stringNumber3 = "123";
            int intNumber6 = 10;
            Console.WriteLine(stringNumber3 + intNumber6);
 
            //字符串类型和数字类型其他操作 都是不允许的
            //Console.WriteLine(stringNumber3 - intNumber6);
            //Console.WriteLine(stringNumber3 * intNumber6);
            //Console.WriteLine(stringNumber3 / intNumber6);
            //Console.WriteLine(stringNumber3 % intNumber6);
 
            //单字符和数字类型
            //单字符ascii表对应的10进制数字和数字类型进行数学运算
            char charNumber = 'a';
            int intNumber7 = 10;
            //得到对应的单字符ASCII值
            int charNumber1 = (int)charNumber;
 
            Console.WriteLine(charNumber1);
            Console.WriteLine(charNumber + intNumber7);
            Console.WriteLine(charNumber - intNumber7);
            Console.WriteLine(charNumber * intNumber7);
            Console.WriteLine(charNumber / intNumber7);
            Console.WriteLine(charNumber % intNumber7);
 
 
            //++  --  
            int intNumber9 = 10;
            intNumber9++;
            ++intNumber9;
            //                      12                14             13                 13                                          
            int SumIntNumber = (intNumber9++) + (++intNumber9) - (--intNumber9) + (intNumber9--);
            //26
            Console.WriteLine(SumIntNumber);
            //12
            Console.WriteLine(intNumber9);
 
 
            
 
 
           
            Console.ReadKey();

5.关系运算符

> < >= <= == !=

 // 关系运算符 
 
            int intNumber10 = 10;
            int intNumber11 = 20;
            bool isTrue = intNumber10 < intNumber11;
            Console.WriteLine(isTrue);
            string stringNumber10 = "10";
            //字符串无法和数字类型比较
            //bool isTrue1 =  intNumber10 < stringNumber10;
            char charNumber10 = 'a';
            bool isTrue2 =intNumber10 < charNumber10;
            Console.WriteLine(isTrue2);
            // > >=  <=  同上
 
 
            // ==    !=
            int intNumber12 = 100;
            int intNumber13 = 200;
 
            bool isTrue3 = intNumber12 ==intNumber13;
            bool isTrue4 = intNumber12 != intNumber13;
 
            //字符串类型之间  ==  != 都能使用
            string stringNumber12 = "123";
            string stringNumber13 = "abc";
            char charNumber12 = 'b';
            bool isTrue5 = stringNumber12 == stringNumber13;
            bool isTrue6 = stringNumber12 != stringNumber13;
            bool isTrue7 = charNumber12 == 97;
 
      
 
            //sizeof()	返回数据类型的大小。
            Console.WriteLine(sizeof(int));
            Console.WriteLine(sizeof(long));
 
 
            //判断数据类型方式 GetType()
            int intNumber16 = 10;
            long longNumber17 = 20;
            Console.WriteLine(longNumber17.GetType());
            Console.WriteLine(intNumber16.GetType());