2014-12-14 Jump statement, while loop, usage of various classes

Jump statement: Break

Example: for (int i=0;; i++) //no judgment condition, i.e. forever satisfying condition, infinite loop

{

Console.WriteLine ("Hello world!");

if (i==9)

{

Break Jump out of the loop when i=9

}

Continue

if (i==2)

{

Continue //End Subsequent statements after continue, jump directly to the state change, start the next loop

}

While loop: Returns True or False

int i=0; Initial

while (i<=9)

{

Console.WriteLine ("Hello");

i++; //State change (written in curly braces)

}

Do...while ...

int i=0;

do{

i++;

Console.WriteLine (i);

} while (i<0); //The output is 1, because the condition is judged after, the execution process before, each time needs to execute once i++, then Judge I<0.

Exception statement: Prevent program interruption, continue to execute later

while (true)

{

int i;

Try

{

String s= "1.23";

int I=int.parse (s);

---(Console.WriteLine (i); //1.23 cannot be converted to int, will error)---

}

catch (Exception e) //exception is a class, E is one of its own names, and the parentheses can write any

{

Console.WriteLine (E.massage); //Output error reason

Continue

}

Console.WriteLine (i);

Break

}

Or:

catch (Exception e)

{

Console.WriteLine (E.massage);

}

Finally

{

Console.WriteLine (i);

Console.WriteLine ("Eventually will execute finally" regardless of the error);

}

Type

String Class: The String class is a class that contains many methods and properties for handling strings

String

String s= "Hello";

int i=s.length; Gets the length of the string, returning an int value

Console.WriteLine (i)//output result is 5

String s= "Hello"

S=s.trim (); //Remove spaces before and after the string

S.trimstart () //Remove the front space

s.trimend () //Remove the trailing spaces

s.toupper () //Convert to uppercase

s.tolower () //Convert to lowercase

string is indexed, starting from 0

String ss= "abcdef123";

int Cc=ss. IndexOf ("CD");

Console.WriteLine (CC); //result is 2, starting from 0, 0, 1, 2,cd in 2 position

String ss= "Abcdef1cd23";

int Cc=ss.Last IndexOf ("CD");

Console.WriteLine (CC); //Results for 7,last the location of the last CD, starting from 0

bool B1=ss. StartsWith ("AB") //Determine if a string starts with AB

bool B2=ss. EndsWith ("All") //judge whether to end with 23

Console.WriteLine (ss. Contains ("CD")) //Determine if the string contains a CD character segment

Substring: Intercepting strings

Ss. Substring (2,3); //Starting at 2 (third position), intercept 3

Ss. Substring (2) //starting from 2 position, intercept to the last

Math class

I=math. ABS\SQRT\CEILING\FLOOR\ROUND\PI (i)

DateTime class

DateTime d=new datetime (1990,01,01);

TimeSpan t=new TimeSpan (3,0,0,0); //parentheses inside for adding days, hours, minutes, seconds

D=d.add (t);

or directly add the time directly using the following statement: D=d.adddays (3); AddHours ... Wait a minute

DateTime.Now //Get system Current time

int s=d.dayofyear;

Console.WriteLine (s); //Today is today's number of days, return int type

Console.WriteLine (D.dayofweek); //Return to Sunday, week

String ss=d.tostring ("yyyy mm month DD day hh" mm min ss sec ");

Double dd=1.234;

Ss=dd.  ToString ("#.00"); //#为整数位部分,. 00 is two digits after the decimal point 0, or #.#

Example: Judging whether the date is correct

Try

{

DateTime dt=datetime.parse (Console.ReadLine ()); //If not converted, date format is incorrect

Console.WriteLine (DT);

}

Catch

{

Console.WriteLine ("Not the correct effective date")

}

Console. Clear (); Clear information

Example: Mobile number Lottery

String s= "12333333333"

for (int i=0;i<=100,i++)

{

Console. Writeline (s);

Thread.Sleep (20); //In parentheses for milliseconds, the whole sentence means how many milliseconds to delay

Console.clear ();

Console.WriteLine ("14566667777")

Thread.Sleep (20);

Console.clear ();

}

2014-12-14 Jump statement, while loop, usage of various classes