Initial commit

Miscellaneous/CSString.cpp

@@ -0,0 +1,195 @@
+// 模仿c++ 自带string类，设计一个字符串类SString，要求至少有以下功能：
+// （1）字符串初始化
+// （2）字符串类对象能相互赋值（重载运算符 =）
+// （3）获得字符串长度
+// （4）字符串连接，通过重载运算符 + 实现
+// （5）字符串显示功能
+// （6）字符串插入功能
+// （7）字符串删除功能
+// （8）取子串功能
+// （9）字符串查找功能
+// （10）字符串比较功能，重载运算符 ==
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int N = 1e6 + 2;
+
+class SString {
+private:
+	char *p;
+	int len;
+
+public:
+	SString();
+	SString(const char *s);
+	SString(const SString &s);
+
+	~SString();
+
+	SString &operator=(const char *s);
+	SString &operator=(const SString &s);
+
+	SString operator+(const char *s) const;
+	SString operator+(const SString &s) const;
+
+	bool operator==(const char *s) const;
+	bool operator==(const SString &s) const;
+
+	int length() const;
+
+	void insert(int pos, const char *s);
+	void insert(int pos, const SString &s);
+
+	void erase(int pos, int n);
+
+	SString substr(int pos, int n) const;
+
+	int find(const char *s) const;
+	int find(const SString &s) const;
+
+	friend ostream &operator<<(ostream &out, const SString &s);
+	friend istream &operator>>(istream &in, SString &s);
+};
+
+ostream &operator<<(ostream &out, const SString &s);
+
+SString::SString() {
+	p = nullptr;
+	len = 0;
+}
+
+SString::SString(const char *s) {
+	len = strlen(s);
+	p = new char[len + 1];
+	strcpy(p, s);
+}
+
+SString::SString(const SString &s) {
+	len = s.len;
+	p = new char[len + 1];
+	strcpy(p, s.p);
+}
+
+SString::~SString() {
+	delete[] p;
+}
+
+SString &SString::operator=(const char *s) {
+	if (p != s) {
+		delete[] p;
+		len = strlen(s);
+		p = new char[len + 1];
+		strcpy(p, s);
+	}
+	return *this;
+}
+
+SString &SString::operator=(const SString &s) {
+	if (this != &s) {
+		delete[] p;
+		len = s.len;
+		p = new char[len + 1];
+		strcpy(p, s.p);
+	}
+	return *this;
+}
+
+SString SString::operator+(const char *s) const {
+	SString temp;
+	temp.len = len + strlen(s);
+	temp.p = new char[temp.len + 1];
+	strcpy(temp.p, p);
+	strcat(temp.p, s);
+	return temp;
+}
+
+SString SString::operator+(const SString &s) const {
+	return *this + s.p;
+}
+
+bool SString::operator==(const char *s) const {
+	return strcmp(p, s) == 0;
+}
+
+bool SString::operator==(const SString &s) const {
+	return *this == s.p;
+}
+
+int SString::length() const {
+	return len;
+}
+
+void SString::insert(int pos, const char *s) {
+	if (pos < 0 || pos > len) {
+		cerr << "Invalid position" << endl;
+		return;
+	}
+	int slen = strlen(s);
+	char *temp = new char[len + slen + 1];
+	strncpy(temp, p, pos);
+	strcpy(temp + pos, s);
+	strcpy(temp + pos + slen, p + pos);
+	delete[] p;
+	p = temp;
+	len += slen;
+}
+
+void SString::insert(int pos, const SString &s) {
+	insert(pos, s.p);
+}
+
+void SString::erase(int pos, int n) {
+	if (pos < 0 || pos >= len || n < 0 || n > len - pos) {
+		cerr << "Invalid arguments" << endl;
+		return;
+	}
+	char *temp = new char[len - n + 1];
+	strncpy(temp, p, pos);
+	strcpy(temp + pos, p + pos + n);
+	delete[] p;
+	p = temp;
+	len -= n;
+}
+
+SString SString::substr(int pos, int n) const {
+	if (pos < 0 || pos >= len || n < 0 || n > len - pos) {
+		cerr << "Invalid arguments" << endl;
+		return SString();
+	}
+	char *temp = new char[n + 1];
+	strncpy(temp, p + pos, n);
+	temp[n] = '\0';
+	SString result(temp);
+	delete[] temp;
+	return result;
+}
+
+int SString::find(const char *s) const {
+	char *pos = strstr(p, s);
+	if (pos == nullptr) {
+		return -1;
+	}
+	else {
+		return pos - p;
+	}
+}
+
+int SString::find(const SString &s) const {
+	return find(s.p);
+}
+
+ostream &operator<<(ostream &out, const SString &s) {
+	out << s.p;
+	return out;
+}
+
+istream &operator>>(istream &in, SString &s) {
+	char t[N];
+	in >> t;
+	s.len = strlen(t);
+	s.p = new char[s.len + 1];
+	strcpy(s.p, t);
+	return in;
+}