我要评论 int32
{
public override bool equals(object obj) {
if (!(obj is int32)) {
return false;
}
return m_value == ((int32)obj).m_value;
}
[system.runtime.versioning.nonversionable]
public bool equals(int32 obj)
{
return m_value == obj;
}
}
double
{
// true if obj is another double with the same value as the current instance. this is
// a method of object equality, that only returns true if obj is also a double.
public override bool equals(object obj) {
if (!(obj is double)) {
return false;
}
double temp = ((double)obj).m_value;
// this code below is written this way for performance reasons i.e the != and == check is intentional.
if (temp == m_value) {
return true;
}
return isnan(temp) && isnan(m_value);
}
public bool equals(double obj)
{
if (obj == m_value) {
return true;
}
return isnan(obj) && isnan(m_value);
}
[system.runtime.versioning.nonversionable]
public static bool operator ==(double left, double right) {
return left == right;
}
}
single
{
public override bool equals(object obj) {
if (!(obj is single)) {
return false;
}
float temp = ((single)obj).m_value;
if (temp == m_value) {
return true;
}
return isnan(temp) && isnan(m_value);
}
public bool equals(single obj)
{
if (obj == m_value) {
return true;
}
return isnan(obj) && isnan(m_value);
}
[system.runtime.versioning.nonversionable]
public static bool operator ==(single left, single right) {
return left == right;
}
}
decimal
{
// checks if this decimal is equal to a given object. returns true
// if the given object is a boxed decimal and its value is equal to the
// value of this decimal. returns false otherwise.
//
[system.security.securitysafecritical] // auto-generated
public override bool equals(object value) {
if (value is decimal) {
decimal other = (decimal)value;
return fcallcompare(ref this, ref other) == 0;
}
return false;
}
[system.security.securitysafecritical] // auto-generated
public bool equals(decimal value)
{
return fcallcompare(ref this, ref value) == 0;
}
[system.security.securitysafecritical] // auto-generated
public static bool operator ==(decimal d1, decimal d2) {
return fcallcompare(ref d1, ref d2) == 0;
}
//暂时不知道此函数内部代码，如有知道还望告知。
//根据测试结果，推测如果两个decimal数相等，返回0
[system.security.securitycritical] // auto-generated
[resourceexposure(resourcescope.none)]
[methodimplattribute(methodimploptions.internalcall)]
[reliabilitycontract(consistency.willnotcorruptstate, cer.success)]
private static extern int fcallcompare(ref decimal d1, ref decimal d2);
}
//t is int 、float、double、decimal、byte、char
t a = 1234567890;//0.1234567890f、0.123456789、1234567890m、(byte)11、'a'
t b = 1234567890;//0.1234567890f、0.123456789、1234567890m、(byte)11、'a'
console.writeline(a == b);//返回true
console.writeline(a.equals(b));//返回true
console.writeline(a.equals((object)b));//返回true
/*
console.writeline((object)a == b);//编译错误：运算符‘==’无法应用与‘object’和‘t’类型操作数
console.writeline(a == (object)b);//编译错误：运算符‘==’无法应用与‘object’和‘t’类型操作数
//console.writeline((object)a == (object)b);//返回false，下面解释为什么是false。这个是引用类型'=='，放到下文介绍
*/
valuetype
{
[system.security.securitysafecritical]
public override bool equals (object obj) {
bcldebug.perf(false, "valuetype::equals is not fast. "+this.gettype().fullname+" should override equals(object)");
if (null==obj) {
return false;
}
runtimetype thistype = (runtimetype)this.gettype();
runtimetype thattype = (runtimetype)obj.gettype();
if (thattype!=thistype) {
return false;
}
object thisobj = (object)this;
object thisresult, thatresult;
// if there are no gc references in this object we can avoid reflection
// and do a fast memcmp
if (cancomparebits(this))
return fastequalscheck(thisobj, obj);
fieldinfo[] thisfields = thistype.getfields(bindingflags.instance | bindingflags.public | bindingflags.nonpublic);
for (int i=0; i<thisfields.length; i++) {
thisresult = ((rtfieldinfo)thisfields[i]).unsafegetvalue(thisobj);
thatresult = ((rtfieldinfo)thisfields[i]).unsafegetvalue(obj);
if (thisresult == null) {
if (thatresult != null)
return false;
}
else
if (!thisresult.equals(thatresult)) {
return false;
}
}
return true;
}
[system.security.securitysafecritical] // auto-generated
[resourceexposure(resourcescope.none)]
[methodimplattribute(methodimploptions.internalcall)]
private static extern bool cancomparebits(object obj);
[system.security.securitysafecritical] // auto-generated
[resourceexposure(resourcescope.none)]
[methodimplattribute(methodimploptions.internalcall)]
private static extern bool fastequalscheck(object a, object b);
}
struct point
{
public double x;
public double y;
public double z;
public point(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
public override bool equals(object obj)
{
if (!(obj is point))
{
return false;
}
if (((point)obj).x == this.x)
{
return true;
}
return false;
}
public bool equals(point obj)
{
if (obj.x == this.x)
{
return true;
}
return false;
}
//运算符“point.operator ==(point, point)”要求也要定义匹配的运算符“!=”
public static bool operator ==(point left, point right)
{
return left.x == right.x;
}
public static bool operator !=(point left, point right)
{
return left.x != right.x;
}
}
point p1 = new point(1, 2, 3);
point p2 = p1;
p1.y = 100;
console.writeline(p1 == p2);//返回true
console.writeline(p1.equals(p2)); // 返回true
console.writeline(p1.equals((object)p2)); // 返回true
struct point
{
public double x;
public double y;
public double z;
public point(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
}
point p1 = new point(1, 2, 3);
point p2 = p1;
console.writeline(p1 == p2);//编译错误：运算符"=="无法应用于"point"和"point"类型的操作数
console.writeline(p1.equals(p2)); // 返回true
console.writeline(p1.equals((object)p2)); // 返回true
p1.y = 100;
console.writeline(p1.equals(p2)); // 返回false
console.writeline(p1.equals((object)p2)); // 返回false
public struct valpoint
{
public double x;
public double y;
public double z;
public valpoint(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
public static bool operator ==(valpoint left, valpoint right)
{
return left.x == right.x;
}
public static bool operator !=(valpoint left, valpoint right)
{
return left.x != right.x;
}
}
public class refpoint
{
public double x;
public double y;
public double z;
public refpoint(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
}
public struct valline
{
public valpoint vpoint; // 值类型成员
public refpoint rpoint; // 引用类型成员
public valline(valpoint vpoint, refpoint rpoint)
{
this.vpoint = vpoint;
this.rpoint = rpoint;
}
public override bool equals(object obj)
{
if (!(obj is valline))
{
return false;
}
if (((valline)obj).vpoint == this.vpoint)
{
return true;
}
return false;
}
public bool equals(valline obj)
{
if (obj.vpoint == this.vpoint)
{
return true;
}
return false;
}
public static bool operator ==(valline left, valline right)
{
return left.vpoint == right.vpoint;
}
public static bool operator !=(valline left, valline right)
{
return left.vpoint != right.vpoint;
}
}
valpoint vpoint = new valpoint(1, 2, 3);
valpoint vpoint2 = new valpoint(1, 2, 3);
valpoint vpoint3 = new valpoint(10, 20, 30);
refpoint rpoint = new refpoint(4, 5, 6);
refpoint rpoint2 = new refpoint(7, 8, 9);
valline p1 = new valline(vpoint, rpoint);
valline p2 = p1;
p2.vpoint = vpoint2;
console.writeline(p1 == p2); //返回true
console.writeline(p1.equals(p2)); //返回true
console.writeline(p1.equals((object)p2)); //返回true
p2 = p1;
p2.vpoint = vpoint3;
console.writeline(p1 == p2); //返回true
console.writeline(p1.equals(p2)); //返回false
console.writeline(p1.equals((object)p2)); //返回false
p2 = p1;
p2.rpoint = rpoint2;
console.writeline(p1 == p2); //返回true
console.writeline(p1.equals(p2)); //返回true
console.writeline(p1.equals((object)p2)); //返回true
public struct valpoint
{
public double x;
public double y;
public double z;
public valpoint(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
}
public class refpoint
{
public double x;
public double y;
public double z;
public refpoint(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
}
public struct valline
{
public valpoint vpoint; // 值类型成员
public refpoint rpoint; // 引用类型成员
public valline(valpoint vpoint, refpoint rpoint)
{
this.vpoint = vpoint;
this.rpoint = rpoint;
}
}
valpoint vpoint = new valpoint(1, 2, 3);
valpoint vpoint2 = new valpoint(1, 2, 3);
valpoint vpoint3 = new valpoint(10, 20, 30);
refpoint rpoint = new refpoint(4, 5, 6);
refpoint rpoint2 = new refpoint(7, 8, 9);
valline p1 = new valline(vpoint, rpoint);
valline p2 = p1;
console.writeline(p1 == p2);//编译错误：运算符"=="无法应用于"point"和"point"类型的操作数
p2.vpoint = vpoint2;
console.writeline(p1.equals(p2)); //返回true
console.writeline(p1.equals((object)p2)); //返回true
p2 = p1;
p2.vpoint = vpoint3;
console.writeline(p1.equals(p2)); //返回false
console.writeline(p1.equals((object)p2)); //返回false
p2 = p1;
p2.rpoint = rpoint2;
console.writeline(p1.equals(p2)); //返回false
console.writeline(p1.equals((object)p2)); //返回false
fieldinfo[] thisfields = thistype.getfields(bindingflags.instance | bindingflags.public | bindingflags.nonpublic);
for (int i=0; i<thisfields.length; i++) {
thisresult = ((rtfieldinfo)thisfields[i]).unsafegetvalue(thisobj);
thatresult = ((rtfieldinfo)thisfields[i]).unsafegetvalue(obj);
if (thisresult == null) {
if (thatresult != null)
return false;
}
else
if (!thisresult.equals(thatresult)) {
return false;
}
}
return true;
string
{
// determines whether two strings match.
[reliabilitycontract(consistency.willnotcorruptstate, cer.mayfail)]
public override bool equals(object obj) {
if (this == null) //this is necessary to guard against reverse-pinvokes and
throw new nullreferenceexception(); //other callers who do not use the callvirt instruction
string str = obj as string;
if (str == null)
return false;
if (object.referenceequals(this, obj))
return true;
if (this.length != str.length)
return false;
return equalshelper(this, str);
}
// determines whether two strings match.
[pure]
[reliabilitycontract(consistency.willnotcorruptstate, cer.mayfail)]
public bool equals(string value) {
if (this == null) //this is necessary to guard against reverse-pinvokes and
throw new nullreferenceexception(); //other callers who do not use the callvirt instruction
if (value == null)
return false;
if (object.referenceequals(this, value))
return true;
if (this.length != value.length)
return false;
return equalshelper(this, value);
}
public static bool operator == (string a, string b) {
return string.equals(a, b);
}
// determines whether two strings match.
[pure]
public static bool equals(string a, string b) {
if ((object)a==(object)b) {
return true;
}
if ((object)a==null || (object)b==null) {
return false;
}
if (a.length != b.length)
return false;
return equalshelper(a, b);
}
[system.security.securitysafecritical] // auto-generated
[reliabilitycontract(consistency.willnotcorruptstate, cer.mayfail)]
private unsafe static bool equalshelper(string stra, string strb)
{
contract.requires(stra != null);
contract.requires(strb != null);
contract.requires(stra.length == strb.length);
int length = stra.length;
fixed (char* ap = &stra.m_firstchar) fixed (char* bp = &strb.m_firstchar)
{
char* a = ap;
char* b = bp;
// unroll the loop
#if amd64
// for amd64 bit platform we unroll by 12 and
// check 3 qword at a time. this is less code
// than the 32 bit case and is shorter
// pathlength
while (length >= 12)
{
if (*(long*)a != *(long*)b) return false;
if (*(long*)(a+4) != *(long*)(b+4)) return false;
if (*(long*)(a+8) != *(long*)(b+8)) return false;
a += 12; b += 12; length -= 12;
}
#else
while (length >= 10)
{
if (*(int*)a != *(int*)b) return false;
if (*(int*)(a+2) != *(int*)(b+2)) return false;
if (*(int*)(a+4) != *(int*)(b+4)) return false;
if (*(int*)(a+6) != *(int*)(b+6)) return false;
if (*(int*)(a+8) != *(int*)(b+8)) return false;
a += 10; b += 10; length -= 10;
}
#endif
// this depends on the fact that the string objects are
// always zero terminated and that the terminating zero is not included
// in the length. for odd string sizes, the last compare will include
// the zero terminator.
while (length > 0)
{
if (*(int*)a != *(int*)b) break;
a += 2; b += 2; length -= 2;
}
return (length <= 0);
}
}
}
{
string a = "a1!";
string b = "a1!";
console.writeline(object.referenceequals(a, b));//返回true,可以判断编译器将a与b所指向的"a1!"优化成一个地方。
}
{
string a = "test";
string b = string.copy(a);
console.writeline(object.referenceequals(a, b));//返回false
}
{
string a = "test";
string b = (string)a.clone();
console.writeline(object.referenceequals(a, b));//返回true
}
{
char[] ch = new char[] { 'a', 'a', '@' };
string a = "aa@";
string b = new string(ch);
console.writeline(object.referenceequals(a, b));//返回false
}
unsafe
{
char[] firstchara = "abc".tochararray();
int length = firstchara.length;
fixed (char* ap = firstchara)
{
for (int i = 0; i < length; i++)
{
console.writeline(*(char*)(ap + i));
}
}
}
unsafe
{
int[] firstchara = new int[] { 1, 20, 300 };
int length = firstchara.length;
fixed (int* ap = firstchara)
{
for (int i = 0; i < length; i++)
{
console.writeline(*(int*)(ap + i));
}
}
}
private unsafe static bool equalshelper(string stra, string strb)
{
contract.requires(stra != null);
contract.requires(strb != null);
contract.requires(stra.length == strb.length);
int length = stra.length;
char[] firstchara = stra.tochararray();
char[] firstcharb = strb.tochararray();
fixed (char* ap = &firstchara[0]) fixed (char* bp = &firstcharb[0])//因无法使用m_firstchar，此处是我自行修改。ps：个人认为m_firstchar是指字符串的第一字符，但是无法证明。
//fixed (char* ap = &stra.m_firstchar) fixed (char* bp = &strb.m_firstchar)
{
char* a = ap;
char* b = bp;
while (length >= 10)
{
if (*(int*)a != *(int*)b) return false;
if (*(int*)(a + 2) != *(int*)(b + 2)) return false;
if (*(int*)(a + 4) != *(int*)(b + 4)) return false;
if (*(int*)(a + 6) != *(int*)(b + 6)) return false;
if (*(int*)(a + 8) != *(int*)(b + 8)) return false;
a += 10; b += 10; length -= 10;
}
// this depends on the fact that the string objects are
// always zero terminated and that the terminating zero is not included
// in the length. for odd string sizes, the last compare will include
// the zero terminator.
while (length > 0)
{
if (*(int*)a != *(int*)b) break;
a += 2; b += 2; length -= 2;
}
return (length <= 0);
}
}
1、fixed (char* ap = &stra.m_firstchar) fixed (char* bp = &strb.m_firstchar)-> fixed (char* ap = &firstchara[0]) fixed (char* bp = &firstcharb[0]) 2、(*(int*)a->获取的数据是两个char值（低位ascii*65536+高位ascii）[低位在前，高位在后]。 [char两个字节,范围u+0000到u+ffff] 3、(*(char*)a->获取的数据是一个char值[见上面测试例子]
{
string a = "abcd";
string b = "abcd";
console.writeline(equalshelper(a,b));//返回true
}
{
string a = "test";
string b = string.copy(a);
console.writeline(equalshelper(a, b));//返回true
}
{
string a = "test";
string b = (string)a.clone();
console.writeline(equalshelper(a, b));//返回true
}
{
char[] ch = new char[] { 'a', 'a', '@' };
string a = "aa@";
string b = new string(ch);
console.writeline(equalshelper(a, b));//返回true
}
object
{
public virtual bool equals(object obj)
{
return runtimehelpers.equals(this, obj);//无法查到详细代码
}
public static bool equals(object obja, object objb)
{
if (obja==objb) {
return true;
}
if (obja==null || objb==null) {
return false;
}
return obja.equals(objb);
}
[reliabilitycontract(consistency.willnotcorruptstate, cer.success)]
[system.runtime.versioning.nonversionable]
public static bool referenceequals (object obja, object objb) {
return obja == objb;
}
}
public class refpoint
{
public double x;
public double y;
public double z;
public refpoint(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
}
refpoint p1 = new refpoint(4, 5, 6);
refpoint p2 = p1;
console.writeline(p1.equals(p2));//返回true
console.writeline(object.equals(p1, p2));//返回true
console.writeline(object.referenceequals(p1, p2));//返回true
console.writeline(p1 == p2);//返回true
p2 = new refpoint(4, 5, 6);//虽然值一样，但是引用对象不一样
console.writeline(p1.equals(p2));//返回false
console.writeline(object.equals(p1, p2));//返回false
console.writeline(object.referenceequals(p1, p2));//返回false
console.writeline(p1 == p2);//返回false
public class refpoint
{
public double x;
public double y;
public double z;
public refpoint(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
public override bool equals(object obj)
{
if (!(obj is refpoint))
{
return false;
}
if (((refpoint)obj).x == this.x)
{
return true;
}
return false;
}
public bool equals(refpoint obj)
{
if (obj.x == this.x)
{
return true;
}
return false;
}
public static bool operator ==(refpoint left, refpoint right)
{
return left.x == right.x;
}
public static bool operator !=(refpoint left, refpoint right)
{
return left.x != right.x;
}
}
refpoint p1 = new refpoint(4, 5, 6);
refpoint p2 = p1;
console.writeline(p1.equals(p2));//返回true
console.writeline(object.equals(p1, p2));//返回true
console.writeline(object.referenceequals(p1, p2));//返回true
console.writeline(p1 == p2);//返回true
p2 = new refpoint(4, 50, 60);
console.writeline(p1.equals(p2));//返回true
console.writeline(object.equals(p1, p2));//返回true
console.writeline(object.referenceequals(p1, p2));//返回false
console.writeline(p1 == p2);//返回true
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