How to avoid memory leaks in C++?

Memory leaks will cause a waste of system memory, and may even lead to system crashes and other consequences. So how to avoid memory leaks? The following article will introduce you to some memory leaks in C and learn how to avoid memory leaks. I hope it will be helpful to you. [Video tutorial recommendation: C Tutorial]

Memory leak

Memory Leak refers to the situation where the dynamically allocated memory in the program fails to be released or cannot be released due to some reasons (negligence or error). It will cause a waste of system memory, cause the program to slow down, or even cause serious problems such as system crash. as a result of.

Memory leak defects are hidden and cumulative, making them difficult to detect. Because the memory leak occurs because the memory block is not released, it is an omission defect rather than a fault defect.

Memory leaks in C

When the programmer allocates memory using the new keyword and forgets to use the Delete() function or Delete[ Memory leaks occur when the ] operator reallocates memory. Using the wrong delete operator is one of the most common memory leaks in C.

The delete operator should be used to release a single allocated memory space, while the delete[] operator should be used to release an array of data values.

Example:

#include <bits/stdc++.h> 
using namespace std; 
  
// 内存泄漏函数
void func_to_show_mem_leak() 
{ 
    int* ptr = new int(5); 
  
    // 主体
  
    // 返回而不释放ptr
    return; 
} 
int main() 
{ 
  
    // 调用函数来处理内存泄漏
    func_to_show_mem_leak(); 
  
    return 0; 
}

How to avoid memory leaks?

1. Instead of manually managing memory, try using smart pointers where applicable.

2. Use std::string instead of char*. The std::string class handles all memory management internally, and it's fast and well optimized.

3. Do not use raw pointers unless you want to interface with the old lib.

4. The best way to avoid memory leaks in C is to make as few new/delete calls as possible at the program level - preferably none. Anything that requires dynamic memory should be hidden in a raid object, releasing the memory when it goes out of scope. raai allocates memory in the constructor and frees it in the destructor so that the memory can be freed when the variable leaves the current scope.

5. For functions that use memory allocation, remember to use the function you want to use to release the memory. You can always write code between new and delete, allocating memory through the new keyword and deallocating the memory through the delete keyword.

6. Develop good coding habits and detect whether memory leaks occur in program segments involving memory.

Example:

#include <bits/stdc++.h>
using namespace std;
  
// 内存泄漏函数
void func_to_handle_mem_leak()
{
    int* ptr = new int(5);
  
    // 主体
  
    // 使用delete删除指针ptr
    delete (ptr);
} 

int main()
{
  
    // 调用函数来处理内存泄漏
    func_to_handle_mem_leak()
  
        return 0;
}

Explanation: There is no memory waste in this example because when we come out of the function, we use the delete function to reallocate the memory.

The above is the detailed content of How to avoid memory leaks in C++?. For more information, please follow other related articles on the PHP Chinese website!