实验3：作业魔改版（plugless）

.gitignore

@@ -23,4 +23,6 @@
 # CMake
 cmake-build-*/
 
-out/
+out/
+
+.vs/

work20220407/.idea/.gitignore

@@ -0,0 +1,8 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

work20220407/.idea/deployment.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="PublishConfigData" remoteFilesAllowedToDisappearOnAutoupload="false">
+    <serverData>
+      <paths name="remote_linux (563cc454-127a-4c53-a847-5bf281087bb1)">
+        <serverdata>
+          <mappings>
+            <mapping local="$PROJECT_DIR$" web="/" />
+          </mappings>
+        </serverdata>
+      </paths>
+    </serverData>
+  </component>
+</project>

work20220407/.idea/encodings.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding" defaultCharsetForPropertiesFiles="UTF-8">
+    <file url="file://$PROJECT_DIR$/string/String.cpp" charset="UTF-8" />
+    <file url="file://$PROJECT_DIR$/string/String.h" charset="UTF-8" />
+    <file url="PROJECT" charset="UTF-8" />
+  </component>
+</project>

work20220407/.idea/misc.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
+</project>

work20220407/.idea/modules.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/work20220401.iml" filepath="$PROJECT_DIR$/.idea/work20220401.iml" />
+    </modules>
+  </component>
+</project>

work20220407/.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/.." vcs="Git" />
+  </component>
+</project>

work20220407/.idea/work20220401.iml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module classpath="CMake" type="CPP_MODULE" version="4" />

work20220407/main.cpp

@@ -1,9 +1,9 @@
 #include <iostream>
 #include "string/String.h"
 
-
 using namespace std;
 
+// 测试示例来自题目
 int main() {
     String s1("Help!"),s2("Good!"),s3(s2),s4,s5;
     cout<<"s1="<<s1<<endl;
@@ -15,12 +15,10 @@ int main() {
     cout<<"s3="<<s3<<endl;
     cin>>s4;
     cout<<"s4="<<s4<<endl;
-    cout<<"s4length="<<s4.Length()<<endl;
-
-    /*s5=s3+s4;
+    s5=s3+s4;
     cout<<"s5="<<s5<<endl;
     s5[0]='g';
     cout<<"s5="<<s5<<endl;
-    cout<<"strlen(s5)="<<s5.Length()<<endl;*/
+    cout<<"strlen(s5)="<<s5.Length()<<endl;
     cout<<boolalpha<<(s3 == s1)<<endl;
 }

work20220407/string/String.cpp

@@ -77,14 +77,7 @@ bool String::equals(const char *source, int sourceLength) const {
         }
     }
 
-    // 以上情况都不符合时才进行逐字比较
-    // 能执行到此处两者长度肯定相等，因此访问数组不会越界
-    for (int i = 0; i < length; ++i) {
-        if (data[i] != source[i]) {
-            return false;
-        }
-    }
-    return true;
+    return strcmp(this->data, source) == 0;
 }
 
 String &String::operator=(const String &source) {
@@ -98,6 +91,15 @@ String &String::operator=(const String &source) {
 }
 
 String &String::operator=(const char *source) {
+    if (source == nullptr) {
+        delete[] data;
+        this->data = nullptr;
+        length = 0;
+        allocSize = 0;
+
+        return *this;
+    }
+
     copyData(source, (int) strlen(source));
 
     return *this;
@@ -144,7 +146,7 @@ void String::addString(const char *source, int sourceLength) {
 
     // 本对象nullptr的话就直接新分配
     if (data == nullptr) {
-        allocSize = sourceLength + 2 + 1;
+        allocSize = sourceLength + 1;
         this->data = new char[allocSize]();
 
         length = sourceLength;
@@ -153,13 +155,13 @@ void String::addString(const char *source, int sourceLength) {
     }
 
     // 如果拼接后字符长度超过已分配的内存大小，则重新分配data内存大小
-    if (allocSize < (length + sourceLength + 2)) {
+    if (allocSize < (length + sourceLength + 1)) {
         // 保存拼接前的原数据，以便重新分配足够的内存
         char *old = new char[length + 1]();
         strcpy(old, data);
 
         // 重新分配内存，防止拼接后溢出，2为两个横杠大小
-        length += sourceLength + 2;
+        length += sourceLength;
         allocSize = length + 1;
 
         delete[] data;
@@ -169,6 +171,7 @@ void String::addString(const char *source, int sourceLength) {
     }
 
     strcat(data, source);
+    length += sourceLength;
 }
 
 /**
@@ -202,26 +205,25 @@ std::istream &operator>>(std::istream &inputStream, String &source) {
     return inputStream;
 }
 
-char String::operator[](int i) {
-    return (i < length && i >= 0) ? data[i] : '\0';
+char &String::operator[](int i) {
+    return (i < length && i >= 0) ? data[i] : data[0];
 }
 
 /**
  * 加号运算重载，注意，每次加号运算都会产生一个新的对象
+ * 这里不用引用返回是因为返回局部对象不是安全的
  */
-String &String::operator+(const char *source) {
+String String::operator+(const char *source) {
     int sourceLength = (int) strlen(source);
 
-    String target(this->length + sourceLength + 1);
-    target = this->data;
+    String target(this->data, this->length + sourceLength + 1);
     target += source;
 
     return target;
 }
 
-String &String::operator+(const String &source) {
-    String target(this->length + source.length);
-    target = this->data;
+String String::operator+(const String &source) {
+    String target(this->data, this->length + source.length);
     target += source;
 
     return target;

work20220407/string/String.h

@@ -54,15 +54,15 @@ public:
 
     String &operator=(const char *source);
 
-    String &operator+(const char *source);
+    String operator+(const char *source);
 
-    String &operator+(const String &source);
+    String operator+(const String &source);
 
     friend std::ostream &operator<<(std::ostream &outputStream, const String &source);
 
     friend std::istream &operator>>(std::istream &outputStream, String &source);
 
-    char operator[](int i);
+    char &operator[](int i);
 
     int Length() const;