用汇编的眼光看C++（之算术符重载陷阱）
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在算术符重载里面，“=”重载可能是最经常使用的一种。但是好多人就误以为在函数中，凡是类出现“=”的地方，那就是调用算术符重载，其实不然。为什么呢？我们可以看看下面的代码。首先，我们定义一个基本类：
class data
{
char* value;
int number;
public:
explicit data(int num = 0){
if(num){
number = num;
value = (char*)malloc(num);
}
}
data(const data& d){
number = d.get_number();
value = (char*)malloc(d.get_number());
memmove(value, d.get_point(), d.get_number());
}
~data(){
if(number)
free(value);
}
data& operator=(const data& d){
if(number)
free(value);
number = d.get_number();
value = (char*)malloc(d.get_number());
memmove(value, d.get_point(), d.get_number());
return *this;
}
int get_number() const {return number;}
char* get_point() const {return value;}
};
class data
{
char* value;
int number;
public:
explicit data(int num = 0){
if(num){
number = num;
value = (char*)malloc(num);
}
}
data(const data& d){
number = d.get_number();
value = (char*)malloc(d.get_number());
memmove(value, d.get_point(), d.get_number());
}
~data(){
if(number)
free(value);
}
data& operator=(const data& d){
if(number)
free(value);
number = d.get_number();
value = (char*)malloc(d.get_number());
memmove(value, d.get_point(), d.get_number());
return *this;
}
int get_number() const {return number;}
char* get_point() const {return value;}
};
定义好了函数之后，我们就开始对这个类进行调用，同样代码如下所示：
45: data m(10);
0040108D push 0Ah
0040108F lea ecx,[ebp-14h]
00401092 call @ILT+30(data::data) (00401023)
00401097 mov dword ptr [ebp-4],0
46: data p = m;
0040109E lea eax,[ebp-14h]
004010A1 push eax
004010A2 lea ecx,[ebp-1Ch]
004010A5 call @ILT+35(data::data) (00401028)
004010AA mov byte ptr [ebp-4],1
47: p = m;
004010AE lea ecx,[ebp-14h]
004010B1 push ecx
004010B2 lea ecx,[ebp-1Ch]
004010B5 call @ILT+5(data::operator=) (0040100a)
48: }
45: data m(10);
0040108D push 0Ah
0040108F lea ecx,[ebp-14h]
00401092 call @ILT+30(data::data) (00401023)
00401097 mov dword ptr [ebp-4],0
46: data p = m;
0040109E lea eax,[ebp-14h]
004010A1 push eax
004010A2 lea ecx,[ebp-1Ch]
004010A5 call @ILT+35(data::data) (00401028)
004010AA mov byte ptr [ebp-4],1
47:&
补充：软件开发 , C++ ,
