c++中 string ss;是什么意思,谢谢

如题所述

定义一个字符串ss
这个是空的字符串,可赋值,有一堆函数操作
b) string s(str) //拷贝构造函数 生成str的复制品
c) string s(str,stridx) //将字符串str内“始于位置stridx”的部分当作字符串的初值
d) string s(str,stridx,strlen) //将字符串str内“始于stridx且长度顶多strlen”的部分作为字符串的初值
e) string s(cstr) //将C字符串作为s的初值
f) string s(chars,chars_len) //将C字符串前chars_len个字符作为字符串s的初值。
g) string s(num,c) //生成一个字符串,包含num个c字符
h) string s(beg,end) //以区间beg;end(不包含end)内的字符作为字符串s的初值
i) s.~string() //销毁所有字符,释放内存
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第1个回答  2011-07-19
这个头文件在他的主页上有源文件,需要你自己新建一个这个名字的头文件,将内容拷贝进去才可以

给你代码吧:
//文件起名为:std_lib_facilities.h,然后添加到你的项目中
/*
simple "Programming: Principles and Practice using C++" course header to
be used for the first few weeks.
It provides the most common standard headers (in the global namespace)
and minimal exception/error support.

Students: please don't try to understand the details of headers just yet.
All will be explained. This header is primarily used so that you don't have
to understand every concept all at once.

Revised April 25, 2010: simple_error() added
*/

#ifndef H112
#define H112 201004L

#include<iostream>
#include<fstream>
#include<sstream>
#include<cmath>
#include<cstdlib>
#include<string>
#include<list>
#include<vector>
#include<algorithm>
#include<stdexcept>

//------------------------------------------------------------------------------

#ifdef _MSC_VER
#include <hash_map>
using stdext::hash_map;
#else
#include <ext/hash_map>
using __gnu_cxx::hash_map;

namespace __gnu_cxx {

template<> struct hash<std::string>
{
size_t operator()(const std::string& s) const
{
return hash<char*>()(s.c_str());
}
};

} // of namespace __gnu_cxx
#endif

//------------------------------------------------------------------------------

#define unordered_map hash_map

//------------------------------------------------------------------------------

typedef long Unicode;

//------------------------------------------------------------------------------

using namespace std;

template<class T> string to_string(const T& t)
{
ostringstream os;
os << t;
return os.str();
}

struct Range_error : out_of_range { // enhanced vector range error reporting
int index;
Range_error(int i) :out_of_range("Range error: "+to_string(i)), index(i)
};

// trivially range-checked vector (no iterator checking):
template< class T> struct Vector : public std::vector<T> {
typedef typename std::vector<T>::size_type size_type;

Vector()
explicit Vector(size_type n) :std::vector<T>(n) {}
Vector(size_type n, const T& v) :std::vector<T>(n,v) {}
template <class I>
Vector(I first, I last) :std::vector<T>(first,last) {}

T& operator[](unsigned int i) // rather than return at(i);
{
if (i<0||this->size()<=i) throw Range_error(i);
return std::vector<T>::operator[](i);
}
const T& operator[](unsigned int i) const
{
if (i<0||this->size()<=i) throw Range_error(i);
return std::vector<T>::operator[](i);
}
};

// disgusting macro hack to get a range checked vector:
#define vector Vector

// trivially range-checked string (no iterator checking):
struct String : std::string {

String()
String(const char* p) :std::string(p) {}
String(const string& s) :std::string(s) {}
template<class S> String(S s) :std::string(s) {}
String(int sz, char val) :std::string(sz,val) {}
template<class Iter> String(Iter p1, Iter p2) : std::string(p1,p2)

char& operator[](unsigned int i) // rather than return at(i);
{
if (i<0||size()<=i) throw Range_error(i);
return std::string::operator[](i);
}

const char& operator[](unsigned int i) const
{
if (i<0||size()<=i) throw Range_error(i);
return std::string::operator[](i);
}
};

#ifndef _MSC_VER
namespace __gnu_cxx {

template<> struct hash<String>
{
size_t operator()(const String& s) const
{
return hash<std::string>()(s);
}
};

} // of namespace __gnu_cxx
#endif

struct Exit : runtime_error {
Exit(): runtime_error("Exit") {}
};

// error() simply disguises throws:
inline void error(const string& s)
{
throw runtime_error(s);
}

inline void error(const string& s, const string& s2)
{
error(s+s2);
}

inline void error(const string& s, int i)
{
ostringstream os;
os << s <<": " << i;
error(os.str());
}

#if _MSC_VER<1500
// disgusting macro hack to get a range checked string:
#define string String
// MS C++ 9.0 have a built-in assert for string range check
// and uses "std::string" in several places so that macro substitution fails
#endif

template<class T> char* as_bytes(T& i) // needed for binary I/O
{
void* addr = &i; // get the address of the first byte
// of memory used to store the object
return static_cast<char*>(addr); // treat that memory as bytes
}

inline void keep_window_open()
{
cin.clear();
cout << "Please enter a character to exit\n";
char ch;
cin >> ch;
return;
}

inline void keep_window_open(string s)
{
if (s=="") return;
cin.clear();
cin.ignore(120,'\n');
for (;;) {
cout << "Please enter " << s << " to exit\n";
string ss;
while (cin >> ss && ss!=s)
cout << "Please enter " << s << " to exit\n";
return;
}
}

// error function to be used (only) until error() is introduced in Chapter 5:
inline void simple_error(string s) // write ``error: s�� and exit program
{
cerr << "error: " << s << '\n';
keep_window_open(); // for some Windows environments
exit(1);
}

// make std::min() and std::max() accessible:
#undef min
#undef max

#include<iomanip>
inline ios_base& general(ios_base& b) // to augment fixed and scientific
{
b.setf(ios_base::fmtflags(0),ios_base::floatfield);
return b;
}

// run-time checked narrowing cast (type conversion):
template<class R, class A> R narrow_cast(const A& a)
{
R r = R(a);
if (A(r)!=a) error(string("info loss"));
return r;
}

inline int randint(int max)

inline int randint(int min, int max)

inline double sqrt(int x) // to match C++0x

#endif
第2个回答  2011-07-15
这个是 c++中标准的字符容器。
第3个回答  2011-07-15
定义一个string的变量ss
第4个回答  2011-07-15
就是一个string类型的变量,叫ss,搞得这么复杂干吗?
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