Cross-platform differences in C++ memory management

C++ memory management has subtle differences on different platforms, including: Heap allocation: new automatically initializes memory on Windows, while explicit initialization is required on Linux. Pointer arithmetic: The ++ operator points to the next element on Windows and the next byte on Linux. Endianness: Big-endian and little-endian methods store integers in different byte order. Debugging information: gdb and lldb have different commands to view the call stack.

Cross-platform differences in C++ memory management

Introduction

Memory management is an important component in C++ development part, but it has subtle differences on different platforms. Understanding these differences is critical to writing portable code.

Heap Allocation

In C++, use the new keyword to allocate memory from the heap. The allocated memory must be freed using the delete keyword. However, new and delete may be implemented slightly differently on different platforms.

Example 1: new

int* arr = new int[10]; // Windows
int* arr = new int[10] {}; // Linux

on Windows and Linux new on Windows will initialize the allocated memory , but not on Linux. Therefore, arrays must be initialized explicitly on Linux.

Pointer arithmetic

Pointer arithmetic is allowed in C++, but its semantics may differ on different platforms.

Example 2: ++ Operator

int* ptr = ...;
++ptr; // Windows: 指向下一个元素
++ptr; // Linux: 指向下一个字节

On Windows, the ++ operator increments the pointer to The address of the next element, while on Linux it increments the pointer to the address of the next byte.

Endianness

Endianness refers to the order in which integers are stored in memory. There are two main endiannesses: big-endian and little-endian.

Example 3: int Endianness of variables

int num = 0x12345678;

// 大端法：12 34 56 78
// 小端法：78 56 34 12

On little-endian platforms, the low-order byte of the number is stored in the lower memory address, while the high-order byte is stored in a higher memory address.

Debug information

Debug information is crucial for debugging your code, but it may be formatted differently on different platforms.

Example 4: gdb and lldb

gdb> info stack // Linux
lldb> bt       // macOS

on Linux using gdb and on When using lldb on macOS, the command to view the call stack is different.

Practical case

The following code example illustrates the cross-platform differences in C++ memory management:

#include <iostream>

int main() {
  // 堆分配
  int* arr = new int[10];

  // 在 Linux 上初始化数组
#ifdef __linux__
  for (int i = 0; i < 10; ++i) {
    arr[i] = i;
  }
#endif

  // 访问数组
  for (int i = 0; i < 10; ++i) {
    std::cout << arr[i] << " ";
  }

  // 释放内存
  delete[] arr;

  return 0;
}

This code runs cross-platform, running on Windows and Produces the same results on Linux.

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