企业官网建设流程全解析

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; }