People who study Python transfer to C The most direct confusion is: Why can't they write like Python? Because C, although the syntax is more complex, provides underlying control capabilities and performance advantages. 1. In terms of syntax structure, C uses curly braces {} instead of indentation to organize code blocks, and variable types must be explicitly declared; 2. In terms of type system and memory management, C does not have an automatic garbage collection mechanism, and needs to manually manage memory and pay attention to freeing resources. RAII technology can assist resource management; 3. In function and class definitions, C needs to explicitly access modifiers, constructors and destructors, and supports advanced functions such as operator overloading; 4. In terms of standard libraries, STL provides powerful containers and algorithms, but needs to adapt to generic programming ideas; 5. Common pitfalls include adding semicolons after each statement, using std:: to access the namespace, including necessary header files, and separation of the compilation and operation process. Mastering these key differences will help Python developers transition smoothly to C.

People who study Python transfer to C, the most direct confusion is: Why can't they write like Python? C looks more complex and wordy, but its underlying control capabilities and performance advantages are irreplaceable by Python. This article starts from the perspective of a developer familiar with Python and helps you quickly understand the core differences and key usage of C.

Basic syntax structure: no indentation coercion, type must be declared

Python organizes code blocks by indentation, while C uses curly braces {} . This may not be used to at first, but after adapting, it is actually more free, especially when writing complex logic.

More importantly, C must declare variable types , unlike Python that can dynamically assign values:

 int age = 25;
std::string name = "Alice";

Compare Python:

 age = 25
name = "Alice"

You will find C is "verbose" to write, but this explicit declaration helps compiler optimization and avoid runtime errors.

In addition, the entry function of C is main() , and the return type must be int . Usually, the end of the program is returned to 0 , which means that the program ends normally:

 #include <iostream>
using namespace std;

int main() {
    cout << "Hello, World!" << endl;
    return 0;
}

Type system and memory management: no garbage collection mechanism

This is one of the biggest differences between C and Python. Python has automatic garbage collection (GC), so you don't have to worry about memory leaks. But C does not, memory needs to be managed manually, especially when you use pointers.

For example, you allocate an object on the heap:

 int* p = new int(10);
// Remember to release delete p after use;

If you don't delete it will cause a memory leak. This should be paid special attention to for those who are used to Python's automatic memory management.

There is another concept called "RAII" (Resource Acquisition Is Initialization), which is a very common resource management method in C. For example, file operations, locks, etc. can automatically handle resource release through constructors/destructors.

Functions and classes: object-oriented styles are similar but implementations are different

Python's class definition is very concise, while C's class requires more details, such as access modifiers (public/private), constructors, destructors, etc.

Let’s take a look at a simple class definition:

 class Person {
private:
    std::string name;
public:
    Person(std::string n) : name(n) {}
    void saysHello() {
        std::cout << "Hello, I&#39;m " << name << std::endl;
    }
};

When using:

 Person p("Bob");
p.sayHello();

You will find that C's class needs to declare member variable access permissions first, and the constructor can also use initialization list ( : name(n) ) to improve efficiency.

In addition, C supports operator overloading, template generics, multiple inheritance and other functions. These Python can also be done, but the implementation method is completely different.

Standard and third-party libraries: STL is your new friend

Python has a rich standard library and pip that can hold various packages. Although C's standard library is not that rich, STL (Standard Template Library) is a very powerful tool set, including containers (vector, map, set), algorithms (sort, find) and iterators.

For example, a list in Python can be written like this:

 nums = [1, 2, 3]
nums.append(4)

C corresponds to vector :

 #include <vector>
std::vector<int> nums = {1, 2, 3};
nums.push_back(4);

The design idea of ??STL is generic templates. Although the learning curve is a bit steep, once you master it, you can write efficient and flexible code.

Tips: Reminders of some common pitfalls

• Don't forget the semicolon : C You need to add a semicolon after each statement, which is not required in Python.
• The namespace should be std:: : For example, cout and vector are both in the std namespace.
• Don't omit the header files : each functional module needs to include the corresponding header files, such as <vector></vector> and <iostream></iostream> .
• Compilation and running are separate : after writing the code, you must first compile it into an executable file and then run it, unlike Python that directly explains execution.

Basically that's it. C is indeed more cumbersome than Python, but it is an important step to system-level programming, game development, and high-performance computing. As long as you understand the basic syntax and memory model, the road ahead will be much smoother.

The above is the detailed content of C tutorial for people who know Python. For more information, please follow other related articles on the PHP Chinese website!