Страустрап Бьярн
Шрифт:
string(char *);
inline ~string { delete p; }
void operator=(string&);
string(string&);
};
string::string(char* s)
{
p = new char [size = strlen(s) + 1];
strcpy (p,s);
}
void string::operator=(string& a)
{
if (this == &a) return;
delete p;
p=new char[size=a.size];
strcpy(p,a.p);
}
string::string(string& a)
{
p=new char[size=a.size];
strcpy(p,a.p);
}
string g(string arg)
{
return arg;
}
main
{
string s = "asdf";
s = g(s);
cout ‹‹ s.p ‹‹ "\n";
}
b6_7.cxx
#include ‹stream.hxx›
#include ‹string.h›
struct pair {
char * name;
int val;
};
class assoc {
pair * vec;
int max;
int free;
public:
assoc(int);
int& operator[](char*);
void print_all;
};
assoc::assoc(int s)
{
max = (s‹16) ? s : 16;
free = 0;
vec = new pair[max];
}
int& assoc::operator[](char * p)
/*
maintain a set of "pair"s
search for p,
return a reference to the integer part of its "pair"
make a new "pair" if "p" has not been seen
*/
{
register pair* pp;
for (pp=&vec[free-1]; vec‹=pp; pp--)
if (strcmp(p, pp-›name)-0) return pp-›val;
if (free==max) {// overflow: grow the vector
pair* nvec = new pair[max*2];
for (int i=0; i‹max; i++) nvec[i] = vec[i];
delete vec;
vec = nvec;
max = 2*max;
}
pp = &vec[free++];
pp-›name = new char[strlen(p)+1];
strcpy(pp-›name,p);
pp-›val = 0;
return pp-›val;
}
void assoc::print_all
{
for (int i=0; i‹free; i++)
cout ‹‹ vec[i].name ‹‹ ": " ‹‹ vec[i].val ‹‹ "\n";
}
main
{
const MAX = 256;
char buf[MAX];
assoc vec(512);
while (cin››buf) vec[buf]++;
vec.print_all;
}
b6_8.cxx
#include ‹stream.hxx›
#include ‹string.h›
struct pair {
char* name;
int val;
};
class assoc {
friend class assoc_iterator;
pair* vec;
int max;
int free;
public:
assoc(int);
int& operator[](char*);