Solve the "error: use of deleted function 'function'" problem in C++ code

Solve the "error: use of deleted function 'function'" problem in C code

In C programming, we often encounter various compilation error. One of the common errors is "error: use of deleted function 'function'". This error usually means that we are using a function in our code that has been removed. This article will describe some common causes of this error and how to resolve it, and provide some code examples for reference.

There are many reasons for this error. Here are some common reasons:

1. A deleted function is used. Sometimes we may use some deleted functions in the code. This is often due to the use of outdated libraries or changes in the function interface.
2. No suitable copy constructor is defined for the class. In C, by default, the compiler generates a copy constructor for a class. However, if our class contains some special member variables or uses dynamic data structures such as pointers, then we need to define the copy constructor ourselves. If we do not define a suitable copy constructor for the class, the compiler will default to using the deleted copy constructor, causing this error.
3. The deleted default constructor is used. In some cases, we may need to customize the default constructor. If there is no default constructor defined for a class, the compiler generates one by default. However, if our class contains member variables that cannot be initialized by default, then we need to define a default constructor ourselves. If we do not define a suitable default constructor for the class, the compiler will default to the deleted default constructor, causing this error.

Here are some ways to resolve this error:

1. Check if the used function has been removed. If we use a deleted function in our code, we can consider replacing it with another function or library, or implement the required functionality manually.
2. Check whether a suitable copy constructor is defined for the class. If our class contains some special member variables or uses dynamic data structures such as pointers, then we need to define our own copy constructor to ensure that the object is copied correctly.
3. Check whether a suitable default constructor is defined for the class. If our class contains member variables that cannot be initialized by default, then we need to define a default constructor ourselves to ensure that the object is initialized correctly.

Here are some code examples:

#include <iostream>

class MyClass {
public:
    int* data;

    // 定义拷贝构造函数
    MyClass(const MyClass& other) {
        data = new int(*other.data);
        std::cout << "拷贝构造函数被调用" << std::endl;
    }

    // 定义默认构造函数
    MyClass() {
        data = new int(0);
        std::cout << "默认构造函数被调用" << std::endl;
    }
    
    ~MyClass() {
        delete data;
    }
};

int main() {
    MyClass obj1;
    MyClass obj2 = obj1; // 使用拷贝构造函数

    return 0;
}

In the above code, we define a class named MyClass which contains a Member variable of type int*data. In order to avoid the "error: use of deleted function 'function'" error, we define a copy constructor and a default constructor to ensure the correct initialization and copying of the object.

When we run the above code, the output will be:

默认构造函数被调用
拷贝构造函数被调用

By properly defining the appropriate constructor, we can solve the "error: use of deleted function 'function'" error and ensure Code correctness.

To sum up, when we encounter the "error: use of deleted function 'function'" error in C code, we need to carefully check the code to determine the specific cause, and add, rewrite or replace it as needed related functions to solve this problem. Correctly understanding and solving this error will improve our experience and skills in programming.

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