物联网培训总结(C#)

一:课程[01]【初级基础】：零基础学好C#语法与编程逻辑
1：字符串
字符串常用的方法
Indexof(string) :该方法表示获取该字符的索引，就是找到该字符的位置（索引从0开始）
length; :该方法获取字符串的长度

 //索引从0开始
            string email = @"[email protected]";
            int posipnt = email.IndexOf("@");
            int leng = email.Length;
            Console.WriteLine("@在字符串{0}位置，该字符串的长度为{1}",posipnt,leng);

==和equals方法尽量使用equals
==和equals都表示是否相等,返回布尔值

             string name1 = "xiaowang";
            string name2 = "xiaowang";
            string name3 = "zhangsan";
            Console.WriteLine(name1==name2);//True
            Console.WriteLine(name1.Equals(name2));//True
            Console.WriteLine(name1==name3);//False
            Console.WriteLine(name1.Equals(name3));//False
            

sybstring():截取

            string name4 = "[email protected]";
            string name5 = name4.Substring(0,11);//从下标0到下标11
            string name6 = name4.Substring(name4.IndexOf("@")+1);//从@后开始截取
            Console.WriteLine(name5);
            Console.WriteLine(name6);

Format(占位符,相应参数代换):格式化字符

            string str1 = "我叫{0}，今年{1}岁,来自{2}";
            string str2 = string.Format(str1,"张三",15,"中国");
            Console.WriteLine(str2);

关于空字符
性能从高到底
//string.length0
//string.Empty
//string"";
注：空和null不同,null不存在

           string c = "";
            string d = string.Empty;
            Console.WriteLine(c.Length);//0
            Console.WriteLine(d.Length);//0

Trim()去空格

             string cc = "     jhjjhh     ";
            Console.WriteLine(cc.Trim());// jhjjhh 

  #region ToUpper  转为大写  tolower转为小写
            string str3 = @"hvkahvkakvavve";
            str3 = str3.ToUpper();
            str3 = str3.ToLower();
            Console.WriteLine(str3);
            #endregion


            #region 找到最后一个匹配项的所在的索引(在有多个的情况找到最后一个index第一个)int lastIndeof(string value)
            string str5 = "hattp://www.baidu.com";
            int positon1 = str5.LastIndexOf('m');//从0开始
            Console.WriteLine(positon1);
            #endregion


            #region stringBuilder 可变字符串可追加   string的拼接会不断的开闭空间消耗内存效率不高
            StringBuilder strbuilder = new StringBuilder();
            //在结尾添加
            strbuilder.Append("我正在学习");//append追加
            //在指定位置插入指定字符
            strbuilder.Insert(5,"c#net");
            //移除指定字符
            strbuilder.Remove(7,3);
            Console.WriteLine();
            Console.WriteLine(strbuilder.ToString());//这里writeLine自动给stringBuider添加一个tostring()

            #endregion 

2:数组

 #region ArrayDeclarations and foreach
            //DeclarationsArray
            int[] Scorre = new int[] {67,88,89,90};
            int TotalAchievements = 0;
            //foreach
            for (int i = 0; i < Scorre.Length; i++)
            {
                TotalAchievements += Scorre[i];
            }
            //printing
            Console.WriteLine("TotalAchievements:{0}\nAverrgeScore:{1}",TotalAchievements,TotalAchievements/Scorre.Length);


            #endregion

           

            
            #region foreachUse
            int sum=0;
            /// <summary>
            /// Cyclic Each  Element in the array in turn
            /// </summary>
            foreach (int TotalAchievementsarray in Scorre)
            {
                sum += TotalAchievementsarray;
               
            }
            Console.WriteLine("TotalAchievements:{0}", sum);

            #endregion


            #region string array Operation

            string str= "张三,李四,王五";
            string[] strarray = str.Split(',');
            string str1 = string.Join("_",strarray);
            Console.WriteLine(str1);
            #endregion


            #region Reference data type
            int[] ReferenceArray = new int[] {99 };
            Console.WriteLine("Beforechange:ReferebceArray:{0}",ReferenceArray[0]);
            int[] ReferenceArray2 = ReferenceArray;
            ReferenceArray2 [0]+= 50;
            Console.WriteLine("Afterchange:ReferenceArray:{0},ReferenceArray:{1}",ReferenceArray[0],ReferenceArray2[0]);
            #endregion


            Console.ReadLine();