一、STL
STL(standard template libaray-标准模板库)：是********C++****标准库的重要组成部分，不仅是一个可复用的组件库，而且是一个包罗数据结构与算法的软件框架****。
二、string类基本操作
string类文档介绍
cplusplus.com/reference/string/string/?kw=string
void test_string1()
{
string s1;
string s2("hello world");
string s3(s2);
string s4(s2, 1, 5);
string s5(s2, 1, 60);
string s6(s2, 1);
const char* str = "hello world";
string s7(str, 5);
string s8(100, '#');
cout << s1 << endl;
cout << s2 << endl;
cout << s3 << endl;
cout << s4 << endl;
cout << s5 << endl;
cout << s6 << endl;
cout << s7 << endl;
cout << s8 << endl;
}
void test_string2()
{
string s1("hello world");
//遍历+修改
//下标+[]
s1[0]++;
cout << s1 << endl;
//s1的每个字符都++
for (size_t i = 0; i < s1.size(); i++)
{
s1[i]++;
}
cout << s1 << endl;
//迭代器 [begin(),end()] s1的每个字符都--
//迭代器是所有容器主流的遍历+修改方式
string::iterator it1 = s1.begin();
while (it1 != s1.end())
{
(*it1)--;
++it1;
}
cout << s1 << endl;
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
vector<int>::iterator it2 = v.begin();
while (it2 != v.end())
{
cout << *it2 << " ";
++it2;
}
cout << endl;
list<int> lt;
lt.push_back(1);
lt.push_back(2);
lt.push_back(3);
list<int>::iterator it3 = lt.begin();
while (it3 != lt.end())
{
cout << *it3 << " ";
++it3;
}
cout << endl;
//范围for
auto x = 10;
auto y = 10.1;
cout << x << endl;
cout << y << endl;
int& z = x;
auto& m = z;
m++;
auto p1 = &x;
//只能是指针
auto* p2 = &x;
//自动取容器数据赋值给e
//自动判断结束
//自动迭代
//本质底层也会替换成迭代器，auto e = *迭代器
for (char& e : s1)
{
e--;
}
for (auto e : s1)
{
cout << e << " ";
}
cout << endl;
for (auto e : v)
{
cout << e << " ";
}
cout << endl;
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
int array[] = { 1,2,3,4,5 };
for (int i = 0; i < sizeof(array) / sizeof(array[0]); ++i)
{
cout << array[i] << endl;
}
for (auto e : array)
{
cout << e << " ";
}
cout << endl;
}
void test_string3()
{
string s1("hello world");
const string s2("hello world");
string::iterator it1 = s1.begin();
while (it1 != s1.end())
{
(*it1)--;
++it1;
}
cout << s1 << endl;
string::const_iterator it2 = s2.cbegin();
while (it1 != s2.cend())
{
//(*it2)--;不能修改
++it2;
}
cout << s2 << endl;
string::reverse_iterator it3 = s1.rbegin();
while (it3 != s1.rend())
{
cout << *it3 << " ";
++it3;
}
cout << endl;
string::const_reverse_iterator it4 = s2.rbegin();
while (it4 != s2.rend())
{
cout << *it4 << " ";
++it4;
}
cout << endl;
for (auto ch : s2)
{
cout << ch << " ";
}
cout << endl;
}
void test_string4()
{
string s1("123456");
cout << s1.max_size() << endl;
//均不包含\0
cout << s1.capacity() << endl;
cout << s1.size() << endl;
string s2;
size_t old = s1.capacity();
cout << "capacity:" << old << endl;
for (size_t i = 0; i < 100; i++)
{
s2.push_back('x');
if (s2.capacity() != old)
{
cout << "capacity:" << s2.capacity() << endl;
old = s2.capacity();
}
}
cout << s1 << endl;
s1.clear();
cout << s1 << endl;
cout << "size:" << s2.size() << endl;
cout << "capacity:" << s2.capacity() << endl;
//s2.clear();
for (size_t i = 0; i < 100; i++)
{
s2.pop_back();
}
s2.shrink_to_fit();
cout << "size:" << s2.size() << endl;
cout << "capacity:" << s2.capacity() << endl;
}
void test_string5()
{
string s1("123456");
cout << "size:" << s1.size() << endl;
cout << "capacity:" << s1.capacity() << endl;
//确定知道需要多少空间，提前开好，避免扩容，提高效率
s1.reserve(100);
cout << "size:" << s1.size() << endl;
cout << "capacity:" << s1.capacity() << endl << endl;
string s2("123456");
cout << "size:" << s2.size() << endl;
cout << "capacity:" << s2.capacity() << endl;
//插入数据，让size到n个
//n > capacity > size;
s2.resize(20,'x');
cout << s2 << endl;
cout << "size:" << s2.size() << endl;
cout << "capacity:" << s2.capacity() << endl;
//capacity > n > size;
s2.resize(25, 'x');
cout << s2 << endl;
cout << "size:" << s2.size() << endl;
cout << "capacity:" << s2.capacity() << endl;
//删除数据
//n < size
s2.resize(5);
cout << s2 << endl;
cout << "size:" << s2.size() << endl;
cout << "capacity:" << s2.capacity() << endl;
}
void test_string6()
{
string s1("123456");
s1[0]++;
cout << s1 << endl;
//越界检查，断言
s1[15];//s1.operator[](15);
s1.at(0)--;
cout << s1 << endl;
//越界抛异常
s1.at(15);
}
void test_string7()
{
string s1("hello world");
//s1.push_back(' ');
//s1.append("hello bit");
//s1.append(10, 'x');
s1 += ' ';
s1 += "hello world";
cout << s1 << endl;
s1 = 'x';
cout << s1 << endl;
s1.assign(10, 'y');
cout << s1 << endl;
//insert 谨慎使用，涉及底层数据的挪动，效率低下
string s2("hello world");
s2.insert(0, "yyy");
cout << s2 << endl;
s2.insert(0,1,'!');
cout << s2 << endl;
s2.insert(s2.begin(),'!');
cout << s2 << endl;
string s3("hello world");
s3.erase(5, 1);
cout << s3 << endl;
string s4("hello world");
cout << s4 << endl;
s4.replace(5, 1, "#");
cout << s4 << endl;
//所有空格替换为%%
string s5("hello world hello world");
//size_t pos = s5.find(' ');
//while (pos != string::npos)
//{
// s5.replace(pos, 1, "%%");
// pos = s5.find(' ', pos + 2);
//}
//cout << s5 << endl;
string s6;
s6.reserve(s5.size());
for (auto ch : s5)
{
if (ch == ' ')
{
s6 += "%%";
}
else
{
s6 += ch;
}
cout << s6 << endl;
}
}
void test_string8()
{
string filename("test.cpp");
FILE* fout = fopen(filename.c_str(), "r");
if (fout == nullptr)
{
cout << "fopen error" << endl;
return;
}
char ch = fgetc(fout);
while (ch != EOF)
{
cout << ch;
ch = fgetc(fout);
}
}
string findsuffix(const string& filename)
{
size_t i = filename.find('.');
if (i != string::npos)
{
return filename.substr(i);
}
else
{
//string empty;
//return empty;
//return "";
return string();
}
}
vector<string> split_url(const string& url)
{
vector<string> v;
size_t i1 = url.find(":");
if (i1 != string::npos)
{
cout << url.substr(0, i1) << endl;
}
size_t i2 = i1 + 3;
size_t i3 = url.find('/', i2);
if (i3 != string::npos)
{
v.push_back(url.substr(i2, i3 - i2));
v.push_back(url.substr(i3 + 1));
}
return v;
}
void test_string9()
{
string filename1("test.cpp");
string filename2("test.c");
string filename3("test");
string filename4("test.cpp.tar");
cout << findsuffix(filename1) << endl;
cout << findsuffix(filename2) << endl;
cout << findsuffix(filename3) << endl;
cout << findsuffix(filename4) << endl;
string url1 = "http://legacy.cplusplus.com/refernce/string/string/";
string url2 = "ftp://legacy.cplusplus.com/refernce/string/string/";
//split_url(url1);
//split_url(url2);
vector<string> ret = split_url(url1);
}
void test_string10()
{
std::string str("please,replace the vowels in this sentence by asterisks");
std::size_t found = str.find_first_not_of("aeiou");
while (found != std::string::npos)
{
str[found] = '*';
found = str.find_first_not_of("aeiou", found + 1);
}
std::cout << str << '\n';
string s1("xxx");
string s2("xxx11");
const char* str = "232222";
s1 == s2;
s1 == str;
str == s1;
}
int main()
{
//test_string1();
//test_string2();
//test_string3();
//test_string4();
//test_string5();
//try
//{
// test_string6();
//}
//catch (const exception& e)
//{
// cout << e.what() << endl;
//}
//try
//{
// test_string7();
//}
//catch (const exception& e)
//{
// cout << e.what() << endl;
//}
//test_string8();
//test_string9();
//test_string10();
return 0;
}三、string模拟实现
//string.h
#pragma once
#include<string.h>
#include<assert.h>
#include<iostream>
using namespace std;
namespace bit
{
class string
{
public:
typedef char* iterator;
typedef const char* const_iterator;
iterator begin();
iterator end();
const_iterator begin() const;
const_iterator end() const;
//string();
string(const char* str="");
const char* c_str() const;
~string();
string(const string& s);
string& operator=(const string& s);
size_t size() const;
char& operator[](size_t i);
const char& operator[](size_t i) const;
void reserve(size_t n);
void push_back(char ch);
void pop_back();
void append(const char* str);
string& operator+=(char ch);
string& operator+=(const char* str);
string& insert(size_t pos, char ch);
string& insert(size_t pos, const char* str);
string& earse(size_t pos=0, size_t len = npos);
size_t find(char ch, size_t pos = 0) const;
size_t find(const char* str, size_t pos = 0) const;
void clear();
string substr(size_t pos, size_t len = npos) const;
bool operator<(const string& s)const;
bool operator<=(const string& s)const;
bool operator>(const string& s)const;
bool operator>=(const string& s)const;
bool operator==(const string& s)const;
bool operator!=(const string& s)const;
private:
char* _str;
size_t _size;
size_t _capacity;
public:
static const size_t npos;
};
ostream& operator<<(ostream& out, const string& s);
istream& operator>>(istream& in,string& s);
istream& getline(istream& in, string& s, char delim = '\n');
}
//string.cpp
#define _CRT_SECURE_NO_WARNINGS
#include"string.h"
namespace bit
{
const size_t string::npos = -1;
//string::string()
// :_str(new char[1]{'\0'})
// ,_size(0)
// ,_capacity(0)
//{}
string::string(const char* str)
:_size(strlen(str))
{
_capacity = _size;
_str = new char[_size + 1];
//strcpy(_str, str);
memcpy(_str, str, _size + 1);
}
string::~string()
{
delete[] _str;
_str = nullptr;
_size = _capacity = 0;
}
string::string(const string& s)
{
_str = new char[s._capacity + 1];
memcpy(_str, s._str, s._size + 1);
_size = s._size;
_capacity = s._capacity;
}
string& string::operator=(const string& s)
{
if (this != &s)
{
char* tmp = new char[s._capacity + 1];
memcpy(tmp, s._str, s._size + 1);
delete[] _str;
_str = tmp;
_size = s._size;
_capacity = s._capacity;
}
return *this;
}
const char* string::c_str() const
{
return _str;
}
size_t string::size() const
{
return _size;
}
char& string::operator[](size_t i)
{
assert(i < _size);
return _str[i];
}
const char& string::operator[](size_t i) const
{
assert(i < _size);
return _str[i];
}
string::iterator string::begin()
{
return _str;
}
string::iterator string::end()
{
return _str + _size;
}
string::const_iterator string::begin() const
{
return _str;
}
string::const_iterator string::end() const
{
return _str + _size;
}
void string::reserve(size_t n)
{
if (n > _capacity)
{
char* tmp = new char[n + 1];
//strcpy(str, _str);
memcpy(tmp, _str, _size + 1);
delete[] _str;
_str = tmp;
_capacity = n;
}
}
void string::push_back(char ch)
{
if (_size >= _capacity)
{
size_t newcapacity = _capacity == 0 ? 4 : 2 * _capacity;
reserve(newcapacity);
}
_str[_size] = ch;
++_size;
_str[_size] = '\0';
}
void string::pop_back()
{
assert(_size > 0);
--_size;
_str[_size] = '\0';
}
void string::append(const char* str)
{
size_t len = strlen(str);
if (_size + len > _capacity)
{
size_t newcapacity = 2 * _capacity > _size + len ? 2 * _capacity : _size + len;
reserve(newcapacity);
}
//strcpy(_str + _size, str);
memcpy(_str + _size,str, len + 1);
_size += len;
}
string& string::operator+=(char ch)
{
push_back(ch);
return *this;
}
string& string::operator+=(const char* str)
{
append(str);
return *this;
}
string& string::insert(size_t pos, char ch)
{
assert(pos <= _size);
if (_size >= _capacity)
{
size_t newcapacity = _capacity == 0 ? 4 : 2 * _capacity;
reserve(newcapacity);
}
int end = _size;
while (end >= (int)pos)
{
_str[end + 1] = _str[end];
--end;
}
_str[pos] = ch;
++_size;
return *this;
}
string& string::insert(size_t pos, const char* str)
{
assert(pos <= _size);
size_t len = strlen(str);
if (_size + len > _capacity)
{
size_t newcapacity = 2 * _capacity > _size + len ? 2 * _capacity : _size + len;
reserve(newcapacity);
}
int end = _size+len;
while (end > pos+len-1)
{
_str[end] = _str[end-len];
--end;
}
for (size_t i = 0; i < len; i++)
{
_str[pos + i] = str[i];
}
_size += len;
return *this;
}
string& string::earse(size_t pos, size_t len)
{
assert(pos < _size);
//要删除的数据，大于pos后面的字符
//pos后面全删
if (len == npos || len >= (_size - pos))
{
_size = pos;
_str[_size] = '\0';
}
else
{
size_t i = pos + len;
memmove(_str + pos, _str + i, _size + 1 - i);
_size -= len;
}
return *this;
}
size_t string::find(char ch, size_t pos) const
{
for (size_t i = pos; i < _size; i++)
{
if (_str[i] == ch)
{
return i;
}
}
return npos;
}
size_t string::find(const char* str, size_t pos) const
{
const char* p1 = strstr(_str + pos, str);
if (p1 == nullptr)
{
return npos;
}
else
{
return p1 - _str;
}
}
void string::clear()
{
_str[0] = '\0';
_size = 0;
}
string string::substr(size_t pos, size_t len) const
{
if (len == npos || len >= _size - pos)
{
len = _size - pos;
}
string ret;
ret.reserve(len);
for (size_t i = 0; i < len; i++)
{
ret += _str[pos + i];
}
return ret;
}
bool string::operator<(const string& s)const
{
size_t i1 = 0, i2 = 0;
while (i1 < _size && i2 < s._size)
{
if (_str[i1] < s[i2])
{
return true;
}
else if (_str[i1] > s[i2])
{
return false;
}
else
{
++i1;
++i2;
}
}
return i2 < s._size;
}
bool string::operator<=(const string& s)const
{
return *this < s || *this == s;
}
bool string::operator>(const string& s)const
{
return !(*this <= s);
}
bool string::operator>=(const string& s)const
{
return!(*this < s);
}
bool string::operator==(const string& s)const
{
size_t i1 = 0, i2 = 0;
while (i1 < _size && i2 < s._size)
{
if (_str[i1] != s[i2])
{
return false;
}
else
{
++i1;
++i2;
}
}
return i1 == _size && i2 == s._size;
}
bool string::operator!=(const string& s)const
{
return !(*this == s);
}
ostream& operator<<(ostream& out, const string& s)
{
//out << s.c_str();
for (size_t i = 0; i < s.size(); i++)
{
out << s[i];
}
return out;
}
istream& operator>>(istream& in, string& s)
{
s.clear();
char buff[128];
int i = 0;
char ch = in.get();
while (ch != ' ' & ch != '\n')
{
buff[i++] = ch;
if (i == 127)
{
buff[i] = '\0';
s += buff;
i = 0;
}
ch = in.get();
if (i > 0)
{
buff[i] = '\0';
s += buff;
}
}
return in;
}
istream& getline(istream& in, string& s, char delim = '\n')
{
s.clear();
char buff[128];
int i = 0;
char ch = in.get();
while (ch != delim)
{
buff[i++] = ch;
if (i == 127)
{
buff[i] = '\0';
s += buff;
i = 0;
}
ch = in.get();
if (i > 0)
{
buff[i] = '\0';
s += buff;
}
}
return in;
}
}
//test.cpp
#include"string.h"
namespace bit
{
void test_string1()
{
string s1;
cout << s1.c_str() << endl;
string s2("hello world");
cout << s2.c_str() << endl;
for (size_t i = 0; i < s2.size(); ++i)
{
s2[i]++;
}
cout << s2.c_str() << endl;
for (auto ch : s2)
{
cout << ch << " ";
}
cout << endl;
string::iterator it1 = s1.begin();
while (it1 != s1.end())
{
cout << *it1 << " ";
}
cout << endl;
}
void test_string2()
{
const string s1("hello world");
string::const_iterator it1 = s1.begin();
while (it1 != s1.end())
{
cout << *it1 << " ";
++it1;
}
cout << endl;
}
void test_string3()
{
string s1("hello world");
s1.push_back('x');
cout << s1.c_str() << endl;
s1.append("hello hehe");
cout << s1.c_str() << endl;
s1 += 'y';
s1 += "zzzzzz";
cout << s1.c_str() << endl;
string s2("hello world");
s2 += '\0';
s2 += '\0';
s2 += '!';
cout << s2 << endl;
cout << s2.c_str() << endl;
s2 += "yyyyyyyyyyyyy";
cout << s2 << endl;
cout << s2.c_str() << endl;
}
void test_string4()
{
string s1("hello world");
s1.insert(6, 'x');
cout << s1 << endl;
s1.insert(0, 'x');
cout << s1 << endl << endl;
string s2("hello world");
s2.insert(6, 'xxxx');
cout << s2 << endl;
s2.insert(0, 'xxxx');
cout << s2 << endl<<endl;
string s3("hello world");
s3.earse(7);
cout << s3 << endl;
string s4("hello world");
s4.earse(7,100);
cout << s3 << endl;
string s5("hello world");
s5.earse(7,3);
cout << s5 << endl;
s5.pop_back();
s5.pop_back();
s5.pop_back();
cout << s5 << endl;
}
void split_url(const string& url)
{
size_t i1 = url.find(":");
if (i1 != string::npos)
{
cout << url.substr(0, i1) << endl;
}
size_t i2 = i1 + 3;
size_t i3 = url.find('/', i2);
if (i3 != string::npos)
{
cout<<url.substr(i2, i3 - i2)<<endl;
cout<<url.substr(i3 + 1)<<endl;
}
cout << endl;
}
void test_string5()
{
string url1 = "http://legacy.cplusplus.com/refernce/string/string/";
string url2 = "ftp://legacy.cplusplus.com/refernce/string/string/";
split_url(url1);
split_url(url2);
}
void test_string6()
{
string s1("hello"), s2("hello");
string s3("hellox"), s4("hello");
string s5("hello"), s6("hellox");
cout << (s1 < s2) << endl;
cout << (s3 < s4) << endl;
cout << (s5 < s6) << endl;
}
void test_string7()
{
string s1("hello"), s2("hello");
cout << s1 << s2 << endl;
cin >> s1 >> s2;
cout << s1 <<" "<< s2 << endl;
string line;
getline(cin, line, '!');
cout << line << endl;
cin >> s1;
cout << s1 << endl;
cout << s1.size() << endl;
}
void test_string8()
{
string s1("hello"), s2("worldxxxxx");
string s3(s1);
cout << s1 << endl;
cout << s3 << endl;
s1[0] = 'x';
cout << s1 << endl;
cout << s3 << endl;
s1 = s2;
cout << s1 << endl;
cout << s2 << endl;
}
}
int main()
{
//bit::test_string1();
//bit::test_string2();
//bit::test_string3();
//bit::test_string4();
//bit::test_string5();
//bit::test_string6();
//bit::test_string7();
//bit::test_string8();
//cout << typeid(bit::string::iterator).name() << endl;
//cout << typeid(std::string::iterator).name() << endl;
return 0;
}