From JavaScript to C

From JavaScript to C: Web developer guide

As a developer who mainly uses JavaScript, I have been studying C to understand the difference between these two languages ​​and when to choose which language. Let's explore C from the perspective of JavaScript developers, check the key differences between each language, and understand when to use their respective advantages.

Type System: Exchange with security in exchange for flexibility

The biggest difference between JavaScript and C is how they handle the type. In JavaScript, we are used to flexible type systems that allow us to dynamically change the variable type and use dynamic data structures. This flexibility makes JavaScript very suitable for rapid development and processing various data types, but it may also cause runtime errors. If these errors use stricter types of systems, they can be captured early.

C adopts more stringent methods to request developers to clearly explain its type and prevent the type from changing the type after the statement. This strictness may look limited at first, but it helps to capture potential errors during compilation and can produce more reliable code in the production environment.

<code class="language-javascript">let answer = 42;
answer = "forty-two"; // JavaScript 允许这样做
let array = [1, "hello", true]; // 混合类型没问题</code>

Memory management: a new responsibility

<code class="language-c++">int answer = 42;
answer = "forty-two"; // 错误！不能将字符串赋值给整数
std::vector<int> array = {1, "hello", true}; // 错误！不允许混合类型</code>

JavaScript developers are accustomed to automatic memory management, where the garbage collector handles cleaning up in the background. This abstraction makes the development faster and eliminates the potential errors of the entire class, but it is at the cost of sacrificing the fine particle size control of memory usage and performance.

In C, memory management has become our responsibility, and we need to explicitly allocate and release resources. Although this increases the complexity of the development process, it provides precise control of memory use and can generate more efficient procedures when properly processed.

<code class="language-javascript">function createBigArray() {
    const arr = new Array(1000000).fill(0);
    // JavaScript 在不再需要时会自动清理它
}</code>

Hyundai C provides tools that make this process more secure, introduce intelligent pointers and RAII (resource acquisition is initialization) mode. These models help prevent memory leakage while maintaining control of resource management:

<code class="language-c++">void createBigArray() {
    int* arr = new int[1000000]();
    // 我们必须自己清理
    delete[] arr;
}</code>

Performance characteristics

<code class="language-c++">#include <memory>

void saferCreateArray() {
    auto arr = std::make_unique<int[]>(1000000);
    // 当 arr 超出范围时，内存会自动释放
}</code>

Let's see a simple digital calculation example in these two languages:

Although these seem to be very similar, the C version can be executed faster because it:

<code class="language-javascript">// JavaScript
function sumSquareRoots(n) {
    let sum = 0;
    for (let i = 0; i < n; i++) {
        sum += Math.sqrt(i);
    }
    return sum;
}</code>

No explanation or JIT compile code

<code class="language-c++">// C++
#include <cmath>

double sumSquareRoots(int n) {
    double sum = 0.0;
    for (int i = 0; i < n; i++) {
        sum += std::sqrt(i);
    }
    return sum;
}</code>

Optimized by the compiler

With direct hardware access permissions
• The unique C concept
Quote and pointer

Unlike the simple variable system of JavaScript, C has multiple methods to process data:

Class and objects

Although these two languages ​​have objects, Class C is very different:

When to choose C

<code class="language-c++">int number = 42;        // 常规变量
int& reference = number; // number 的引用
int* pointer = &number; // number 内存地址的指针</code>

Although JavaScript is still a great choice for Web development and server -side applications, in some specific cases, C stands out as a better tool. When you need the maximum performance, direct hardware access or in -depth system -level programming, you may consider using C. It is particularly valuable for the development of cross -platform desktop applications or game development. In game development, each millisecond performance is very important, and it is crucial to direct hardware access.

In fact, this means that the creation of computational dense applications that need to squeeze each trace of performance from the hardware, build a complex desktop software that requires native properties, and write native modules to enhance the Node.js application using system -level functions, or Use powerful engines such as Unreal to develop games. These scenes use C's advantages in performance, hardware control and system -level access -in these aspects, although JavaScript is flexible and easy to use, it may not be the best choice.

The decision to choose using C usually depends on the specific requirements of performance, hardware interaction or platform restrictions, which makes it a precious tool when the high -level abstraction and interpretation characteristics of JavaScript become a limited factors.

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