Knowledge point One main function, data type, type conversion

I. Contents of the main function

Output, input

Output:
Console.WriteLine ();
Console.Write ();
1. Output Digital
Console.WriteLine (22);//22
Console.WriteLine (12+44);//56
2. Output text
Console.WriteLine ("ABC");//abc
Console.WriteLine ("78" + "56");//7856
3. Integrated output
Console.WriteLine ("78+56=" + (78 + 56));//78+56=134①

Console.Write ("78+56=");
Console.WriteLine (78 + 56); Ii

The effect of ① effect =②

Input:
String AAA = Console.ReadLine ();

Integrated applications:
Input
string s = Console.ReadLine ();
Output
Console.WriteLine ("What you just entered is:" +s);

Case 1:
Make an adder:
Display: Please enter a number.
Wait for input
Display: Please enter another number
Wait for input
Displays the results of the final operation.

Namespace ConsoleApplication2
{
Class Program

{

static void Main (string[] args)
{Console.WriteLine ("Enter a number");
String A=console.readline ();
Console.WriteLine ("Enter another number");
String B=console.readline ();
Double C =convert.todouble (a) +convert.todouble (b);
Console.WriteLine ("{0}+{1}={2}", a,b,c);
}

}

}

The effect is as follows:

Enter a number

5

Enter a different number

6

5+6=11

Case 2:

static void Main (string[] args)
{
Console.WriteLine ("******** Information Survey Form *********"); Show title
Console.Write ("Name:");
String xm = Console.ReadLine ();
Console.Write ("Gender:");
String xb = Console.ReadLine ();
Console.Write ("Graduate School:");
String byxx = Console.ReadLine ();
Console.Write ("Major in Study:");
String sxzy = Console.ReadLine ();

Show:
Console.WriteLine ("********* just entered the following ************");
Console.WriteLine ("Name:" +xm+ "Gender:" +XB);
Console.WriteLine ("Graduate School:" +BYXX);
Console.WriteLine ("Major in Study:" +sxzy);
}

Case 3:

static void Main (string[] args)
{
Console.WriteLine ("Little hi: What's your name?") ");
Console.Write ("I:");
String xm = Console.ReadLine ();
Console.WriteLine ("Small hi: Oh, so you are the" +xm+ "Ah, too! , what do you like to eat? ");
Console.Write ("I:");
string sw = Console.ReadLine ();
Console.WriteLine ("Small hi: I also like to eat" +sw+ ", you can eat how much ah?) ");
Console.Write ("I:");
String sl = Console.ReadLine ();
Console.WriteLine ("Small hi: you actually eat" +sl+ ", than I eat a lot of");

}

Second, the data type:
1. Basic type
Integer int can only put a finite number of digits-xxxx ~ xxxx, one less than the phone number.
Long
Short

Floating-point Double default decimal number is double
Float if the decimal is to be seen as float, you need to add the suffix ' f,f '
float A = 3.14f;float a = 3.14;//error

Character Char in single quotation marks, only one character can be placed. Except for escape characters
char c = ' a '; char c = "a";//Wrong char c= ' ABC ';//Wrong

boolean bool can only put true,false. The code can only be lowercase and not quoted.
BOOL g = true;bool g = true;//wrong bool g = "true";//Wrong

2. Reference type
String double quotation marks, consisting of one or more characters.
string s = "abcdef"; string s = "a"; string s = ' asdfasdf ';//Wrong

Second, type conversion:
1. Automatic conversion-as long as there is no possibility of data loss, will automatically turn.
2. Casting
For numbers: Add parentheses to the left of the converted value, and write in parentheses about which type to turn to.
float a = (float) 3.14;
For string: The base type to which the string is converted
Method one: int a = Int. Parse ("string"); Float B = float. Parse ("string"); Double c = Double. Parse ("string"); bool D = bool. Parse ("string")
Law II: Using Convert
Double D = convert.todouble (s); float F = convert.tosingle (s);
int a = Convert.ToInt32 (s);

Case 1:

static void Main (string[] args)
{

string s = "4.5";
Double d = Double. Parse (s);
Double D = convert.todouble (s);

Console.WriteLine (d+1);

string s = "4.5";
Double d = Double. Parse (s);
int a = (int) d;
Console.WriteLine (a);

int a = 10;
Float B = (float) 9.8;
Double C = a + B;

A = (int) c;

Console.WriteLine (a);

int a = 4;
Long B = 19;

b = A;

Double c = 3.14;

float F = 2.22f;

c = f;

Char d = ' \a ';
Console.WriteLine (d);

bool G = true;
g = false;
Console.WriteLine (g);

}

Case 2:

static void Main (string[] args)
{

string s = "true";
BOOL B = Convert.toboolean (s);

b =!b;

Console.WriteLine (b);

}

Case 3:

static void Main (string[] args)
{
Console.Write ("How old are you this year?") ");
string s = Console.ReadLine ();
Double age1 = convert.todouble (s);
int age2 = (int) age1;
Console.WriteLine ("You are now {0} years old, next year {1} years old", Age2 + 1,age2);
}

Case 4:

static void Main00 (string[] args)
{

string s = "C:\\text\\new\\aaa.txt";
Console.WriteLine (s);
string s = "Note: \" Puppy "is used to denote intimacy";
Console.WriteLine (s);

char c = ' A '; ASCII code
int b = (int) c;
Console.WriteLine (b);

int a = 43;
char C = (char) A;

Console.WriteLine (c);

for (int i = 0; i <; i++)
//{
char C = (char) i;
Console.Write (i+ "=" +c+ "\ t");
//}
}

Note:

C # escape character: \ ' single quotation mark

\ "Double quotation marks

\\    \

Air

\a Warning

\ nthe line break

\ r Enter

\ t Horizontal tab

Beginner C # language, just a feeling, programmers really not simple.

Knowledge point One main function, data type, type conversion