我在 Bjarne“C++ ...”中实现了 String 类。我想内联 read() 和其他访问器函数，所以我将它们标记为内联。没关系，但是定义对主文件中对类 String 的引用进行读取的哈希函数会给出错误 LNK2019 unresolved external symbol char __thiscall String::read(int)const
为什么这没有解决？
String.h 中的类字符串：
#include <string.h>
class String{
struct Srep{ // representation
char* s; // pointer to elements
int sz; // number of characters
int n; // reference counter
Srep(int nsz, const char* p){
n=1;
sz=nsz;
s=new char[sz+1]; // add space for terminator
strcpy(s,p);
}
~Srep(){delete[]s;}
Srep* get_own_copy(){ // clone if necessary
if(n==1)return this;
n--;
return new Srep(sz,s);
}
void assign(int nsz, const char* p){
if(sz!=nsz){
delete[]s;
sz=nsz;
s=new char[sz+1];
}
strcpy(s,p);
}
private: //prevent copying
Srep(const Srep&);
Srep& operator=(const Srep&);
};
Srep* rep;
public:
class Cref{ // reference to char
friend class String;
String& s;
int i;
Cref(String& ss, int ii):s(ss), i(ii){}
public:
inline operator char(){ // yield value
return s.read(i);
}
inline void operator=(char c){ // change value
s.write(i,c);
}
};
class Range{};
String(); // x=""
String(const char*); // x="abnm'
String(const String&); // x=other_string
String& operator=(const char*);
String& operator=(const String&);
~String();
// access operators
void check(int i)const;
inline char read(int i)const;
void write(int i, char c);
Cref operator[](int i);
char operator[](int i)const;
int size()const;
};
字符串.cpp：
#include "stdafx.h"
#include "String.h"
String::String(){ // the empty string is the default value
rep=new Srep(0,"");
}
String::String(const String& x){ // copy constructor
x.rep->n++;
rep=x.rep; // share representation
}
String::~String(){
if(--rep->n==0)delete rep;
}
String& String::operator=(const String& x){ // copy assignment
x.rep->n++; // protects against "st=st"
if(--rep->n==0)delete rep;
rep=x.rep;
return *this;
}
// pseudo-copy operations taking const char* args are provided to allow
//string literals
String::String(const char* s){
rep=new Srep(strlen(s),s);
}
String& String::operator=(const char* s){
if(rep->n==1) // recycle Srep
rep->assign(strlen(s),s);
else{ //use new Srep
rep->n--;
rep=new Srep(strlen(s),s);
}
return *this;
}
// access operators
inline void String::check(int i)const{
if(i<0||rep->sz<=i)throw Range();
}
inline char String::read(int i)const{ // unchecked access to s
return rep->s[i];
}
inline void String::write(int i, char c){
rep=rep->get_own_copy();
rep->s[i]=c;
}
inline String::Cref String::operator[](int i){
check(i);
return Cref(*this,i);
}
inline char String::operator[](int i)const{// checked access to s
check(i);
return rep->s[i];
}
inline int String::size()const{
return rep->sz;
}
主文件：
// Bjarne_exercise_string.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include "String.h"
int hash(const String& s){
//int h=s.read(0);
//const int max=s.size();
//for(int i=1;i<max;i++){
// h^=s.read(i)>>1; // unchecked access to s (1st take s[i], then rightshift, and then XOR h and this)
//}
//return h;
return 4;
}
int _tmain(int argc, _TCHAR* argv[])
{
String s1;
String s2;
String s3="s3";
String s4("s4");
String s5(s3);
s5=s4;
s3=s4;
//int i=hash(s3);
//i=hash(s1);
return 0;
}