# C++与java的异同

## 1. 基本数据类型：

C++有无类型void和宽字符型wchar\_t，java没有。

## 2. 运算符重载

不像java只能对方法进行重载，C++也支持对运算符进行重载，以实现Object的基本运算。比如：

```cpp
#include <iostream>

using namespace std;

//运算符重载
class Box {
private:
    int length;
    int width;
    int high;
public:
    int getLength() const {
        return length;
    }

    void setLength(int length) {
        Box::length = length;
    }

    int getWidth() const {
        return width;
    }

    void setWidth(int width) {
        Box::width = width;
    }

    int getHigh() const {
        return high;
    }

    void setHigh(int high) {
        Box::high = high;
    }

    //+运算符重载
    Box operator+(const Box& b){
        Box box;
        box.length = this->length + b.length;
        box.high = this->high + b.high;
        box.width = this->width + b.width;
        return box;
    }
};


int main ()
{
    Box box1, box2, box3;
    box1.setHigh(100);
    box1.setWidth(100);
    box1.setLength(100);

    box2.setWidth(200);
    box2.setHigh(200);
    box2.setLength(200);

    box3 = box1 + box2;
    cout << box3.getHigh() << "," << box3.getLength() << "," << box3.getWidth() << endl;
}
```

运行结果：

```
300,300,300
```

## 3. 模板template

C++中的模板类似java中的泛型。

## 4. 函数声明

在C++中函数必须先声明才能使用，一般把声明文件放在.h的头文件中。

## 5. 字符串定义

声明一个字符串有两种方式，一个是使用char数组，一个是使用string类型

```java
// 使用char数组定义字符串
char str1[3] = {'a', 'b', '\0'};//结尾必须加空字符标志\0，否则会被当成字符数组处理
char str2[] = "ab";//也可以这样定义，系统自动加上空白字符\0
// 使用string定义字符串
string c4 = "ab";
```

> 参考：
>
> 《C++ primer plus》
>
> <https://blog.csdn.net/u012485480/article/details/79592072>


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