Beginner with c# 4

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1?￡4 ?¤?¨ò?ààDí￡¨Predefined types￡?

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???aμà￡o*/
int i = 0;
if (i = 0) { // Bug: ó|??ê? (i == 0)
....
}
/* ê???óD?êìaμ??￡μ??úc#?D?áòy·￠ò???±àò?′í?ó￡¨error CS0029: Cannot implicitly convert
type int to bool￡??￡μ±è?￡??a?ù?téüá?ò?μ???óD±?òaμ?áé??D??￡?ò???ùò22??ü?a?ù￡o*/
string str;
....
if(str = Console.ReadLine()) {
  Console.WriteLine("Your comments are: {0}",str);
....
/* ??±?D?￡o*/
using System;
class BoolTest
{
  static void Main() {
    string str = Console.ReadLine();//ò2?éò?￡ostring str;
    if(str == "")                   //        if((str = Console.ReadLine()) == "")
      Console.WriteLine("i cant 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