Beginner with c# 4

1¡£4 Ô¤¶¨ÒåÀàÐÍ£¨Predefined types£©

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¶¼ÖªµÀ£º*/
int i = 0;
if (i = 0) { // Bug: Ó¦¸ÃÊÇ (i == 0)
....
}
/* ÊÇûÓÐÎÊÌâµÄ¡£µ«ÔÚc#ÖлáÒý·¢Ò»¸ö±àÒë´íÎó£¨error CS0029: Cannot implicitly convert
type 'int' to 'bool'£©¡£µ±È»£¬ÕâÑùÎþÉüÁËÒ»µãûÓбØÒªµÄÁé»îÐÔ¡£ÎÒÃÇÔÙÒ²²»ÄÜÕâÑù£º*/
string str;
....
if(str = Console.ReadLine()) {
Console.WriteLine("Your comments are: {0}",str);
....
/* ¶ø±ØÐ룺*/
using System;
class BoolTest
{
static void Main() {
string str = Console.ReadLine();//Ò²¿ÉÒÔ£ºstring str;
if(str == "") // if((str = Console.ReadLine()) == "")
Console.WriteLine("i can't read your comments. Please tell me something! O.K.?");
else
Console.WriteLine("Your comments are: {0}",str);
}
}
/*
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Type Description Examples

object The ultimate base type of all other types object o = new Stack();

string String type; a string is a sequence of string s = "Hello";
Unicode characters

sbyte 8-bit signed integral type sbyte val = 12;

short 16-bit signed integral type short val = 12;

int 32-bit signed integral type int val = 12;

long 64-bit signed integral type long val1 = 12;
long val2 = 34L;

byte 8-bit unsigned integral type byte val1 = 12;
byte val2 = 34U;

ushort 16-bit unsigned integral type ushort val1 = 12;
ushort val2 = 34U;

uint 32-bit unsigned integral type uint val1 = 12;
uint val2 = 34U;

ulong 64-bit unsigned integral type ulong val1 = 12;
ulong val2 = 34U;
ulong val3 = 56L;
ulong val4 = 78UL;

float Single-precision floating point type float value = 1.23F;

double Double-precision floating point type double val1 = 1.23
double val2 = 4.56D;

bool Boolean type; a bool value is either bool value = true;
true or false

char Character type; a char value is a Unicode char value = 'h';
character

decimal Precise decimal type with 28 significant digits decimal value = 1.23M;

ÄãÒ²¿ÉÒÔ×Ô¶¨Òå×Ô¼ºµÄÔ¤¶¨ÒåÀàÐÍ£¬¿ÉÒÔÕâÑù£º*/
using System;
struct Digit
{...}
class Test
{
static void TestInt() {
int a = 1;
int b = 2;
int c = a + b;
Console.WriteLine(c);
}
static void TestDigit() {
Digit a = (Digit) 1;
Digit b = (Digit) 2;
Digit c = a + b;
Console.WriteLine(c);
}
static void Main() {
TestInt();
TestDigit();
}
}
/*
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