1. 变量定义

• C++：

#include <iostream>
int main() {// 定义整型变量int num = 10;// 定义浮点型变量double pi = 3.14159;// 定义字符型变量char ch = 'A';std::cout << "num: " << num << ", pi: " << pi << ", ch: " << ch << std::endl;return 0;
}

// 定义变量（使用 let 或 var，这里用 let，推荐用于块级作用域）
let num = 10;
let pi = 3.14159;
let ch = 'A';
console.log(`num: ${num}, pi: ${pi}, ch: ${ch}`);

2. 数据类型

#include <iostream>
#include <string>
int main() {// 基本数据类型示例int age = 25;float height = 1.75f;  // 注意浮点数后面加 f 表示单精度bool isStudent = true;std::string name = "John";  // 使用标准库中的 string 类型处理字符串std::cout << "Age: " << age << ", Height: " << height << ", Is Student: " << isStudent << ", Name: " << name << std::endl;return 0;
}

let age = 25;
let height = 1.75;
let isStudent = true;
let name = "John";
console.log(`Age: ${age}, Height: ${height}, Is Student: ${isStudent}, Name: ${name}`);

控制结构

1. if-else 语句

• C++：

#include <iostream>
int main() {int score = 80;if (score >= 90) {std::cout << "优秀" << std::endl;} else if (score >= 80) {std::cout << "良好" << std::endl;} else if (score >= 60) {std::cout << "及格" << std::endl;} else {std::cout << "不及格" << std::endl;}return 0;
}

• JavaScript：

let score = 80;
if (score >= 90) {console.log("优秀");
} else if (score >= 80) {console.log("良好");
} else if (score >= 60) {console.log("及格");
} else {console.log("不及格");
}

2. for 循环

• C++：

#include <iostream>
int main() {for (int i = 0; i < 5; i++) {std::cout << i << " ";}std::cout << std::endl;return 0;
}

• JavaScript：

for (let i = 0; i < 5; i++) {console.log(i);
}

3. while 循环

• C++：

#include <iostream>
int main() {int i = 0;while (i < 5) {std::cout << i << " ";i++;}std::cout << std::endl;return 0;
}

• JavaScript：

let i = 0;
while (i < 5) {console.log(i);i++;
}

函数

1. 函数定义与调用

• C++：

#include <iostream>
// 函数声明
int add(int a, int b);
int main() {int result = add(3, 5);std::cout << "结果: " << result << std::endl;return 0;
}
// 函数定义
int add(int a, int b) {return a + b;
}

• JavaScript：

function add(a, b) {return a + b;
}
let result = add(3, 5);
console.log("结果: " + result);

2. 函数参数默认值（C++ 无此特性，JavaScript 有）

• JavaScript：

function greet(name = "Guest") {console.log("Hello, " + name);
}
greet();  // 输出 "Hello, Guest"
greet("John");  // 输出 "Hello, John"

面向对象编程

1. 类定义与对象创建

• C++：

#include <iostream>
class Rectangle {
public:// 构造函数Rectangle(int width, int height) : width(width), height(height) {}int getArea() {return width * height;}
private:int width;int height;
};
int main() {Rectangle rect(5, 3);std::cout << "矩形面积: " << rect.getArea() << std::endl;return 0;
}

• JavaScript：

class Rectangle {constructor(width, height) {this.width = width;this.height = height;}getArea() {return this.width * this.height;}
}
let rect = new Rectangle(5, 3);
console.log("矩形面积: " + rect.getArea());

2. 继承（示例为简单的单继承）

• C++：

#include <iostream>
class Shape {
public:virtual void draw() {std::cout << "绘制形状" << std::endl;}
};
class Circle : public Shape {
public:void draw() override {std::cout << "绘制圆形" << std::endl;}
};
int main() {Shape* shape = new Circle();shape->draw();delete shape;return 0;
}

• JavaScript：

class Shape {draw() {console.log("绘制形状");}
}
class Circle extends Shape {draw() {console.log("绘制圆形");}
}
let shape = new Circle();
shape.draw();

数组操作

1. 数组定义与初始化

• C++：

#include <iostream>
#include <array>
int main() {std::array<int, 5> arr = {1, 2, 3, 4, 5};for (int element : arr) {std::cout << element << " ";}std::cout << std::endl;return 0;
}

• JavaScript：

let arr = [1, 2, 3, 4, 5];
arr.forEach(element => console.log(element));

2. 数组长度获取

• C++：

#include <iostream>
#include <vector>
int main() {std::vector<int> vec = {1, 2, 3, 4, 5};std::cout << "数组长度: " << vec.size() << std::endl;return 0;
}

• JavaScript：

let vec = [1, 2, 3, 4, 5];
console.log("数组长度: " + vec.length);

异常处理（语法不同但功能类似，都是处理运行时错误等情况）

1. C++ 异常处理

#include <iostream>
#include <string>
int main() {try {int num1 = 10;int num2 = 0;if (num2 == 0) {throw std::string("除数不能为零");}int result = num1 / num2;std::cout << "结果: " << result << std::endl;} catch (const std::string& error) {std::cout << "捕获到异常: " << error << std::endl;}return 0;
}

2. JavaScript 异常处理

try {let num1 = 10;let num2 = 0;if (num2 === 0) {throw new Error("除数不能为零");}let result = num1 / num2;console.log("结果: " + result);
} catch (error) {console.log("捕获到异常: " + error.message);
}

以上示例只是 C++ 和 JavaScript 在诸多方面对比的一部分，它们在语法细节、内存管理、运行环境等还有很多不同之处，但这些示例可以帮助你初步了解它们在常见编程任务中的差异与共性。