先决条件： https : //www.geeksforgeeks.org/little-and-big-Endian-mystery/
Little Endian和Big Endian是在机器中存储数据的方式。一些机器可能使用Little Endian字节顺序，而其他机器可能使用big Endian。当您将数据从Big Endian机器传输到Little Endian机器时，这会导致不一致。通常，编译器负责转换。但是，在网络中，Big Endian被用作网络之间数据交换的标准。因此，Little Endian机器需要在通过网络发送数据时将其数据转换为Big Endian。同样，Little Endian机器从网络接收数据时也需要交换字节顺序。
因此，当您通过网络从一台主机到另一台主机发送和接收数据时，Endianness就会成为现实。如果发送方计算机和接收方计算机具有不同的字节序，则需要交换字节序以使其兼容。
因此，重要的是将数据转换为小Endian或大Endian，以便保持一致性和数据完整性。在本文中，我们将研究如何交换数字的字节序。这也是一个常见的面试问题。
方法 ：
- 通过将0x000000FF与之相加来获得数字的最右边8位，因为最后8位全为1，其余均为0，结果将为数字的最右边8位。结果存储在名为leftmost_byte的变量中
- 同样，通过与0x0000FF00相乘获得数字的后8位(从右，右中间)。结果存储在left_middle_byte中
- 通过将数字与0x00FF0000相乘来获得数字的后8位。结果存储在right_middle_byte中
- 最后，通过将数字与0xFF000000相加来获得数字的最左8位。结果存储在rightmost_byte中
- 现在我们已经拥有了数字的所有4个字节，我们需要以相反的顺序将其串联起来。即交换数字的字节序。为此，我们将最右边的8位向左移动24位，以使其成为最左边的8位。我们将右中间字节向左移16(以将其存储为左中间字节)，将左中间字节向左移8(以将其存储为右侧混音字节)。最后，将最左边的字节向左移24。
- 现在，我们在逻辑上“或”(连接)所有变量以获得结果。
考虑数字0x12345678。该数字为4字节宽。在Big Endian中，此数字表示为：
在Little Endian中，相同的数字表示为：
例子：
Input : 0x12345678
Output : 0x78563412
Input : 0x87654321
Output : 0x21436587
实施方式：
C++
// C++ program to print the difference
// of Alternate Nodes
#include
using namespace std;
// Function to swap a value from
// big Endian to little Endian and
// vice versa.
int swap_Endians(int value)
{
// This var holds the leftmost 8
// bits of the output.
int leftmost_byte;
// This holds the left middle
// 8 bits of the output
int left_middle_byle;
// This holds the right middle
// 8 bits of the output
int right_middle_byte;
// This holds the rightmost
// 8 bits of the output
int rightmost_byte;
// To store the result
// after conversion
int result;
// Get the rightmost 8 bits of the number
// by anding it 0x000000FF. since the last
// 8 bits are all ones, the result will be the
// rightmost 8 bits of the number. this will
// be converted into the leftmost 8 bits for the
// output (swapping)
leftmost_byte = (value & 0x000000FF) >> 0;
// Similarly, get the right middle and left
// middle 8 bits which will become
// the left_middle bits in the output
left_middle_byle = (value & 0x0000FF00) >> 8;
right_middle_byte = (value & 0x00FF0000) >> 16;
// Get the leftmost 8 bits which will be the
// rightmost 8 bits of the output
rightmost_byte = (value & 0xFF000000) >> 24;
// Left shift the 8 bits by 24
// so that it is shifted to the
// leftmost end
leftmost_byte <<= 24;
// Similarly, left shift by 16
// so that it is in the left_middle
// position. i.e, it starts at the
// 9th bit from the left and ends at the
// 16th bit from the left
left_middle_byle <<= 16;
right_middle_byte <<= 8;
// The rightmost bit stays as it is
// as it is in the correct position
rightmost_byte <<= 0;
// Result is the concatenation of all these values.
result = (leftmost_byte | left_middle_byle |
right_middle_byte | rightmost_byte);
return result;
}
// Driver Code
int main()
{
// Consider a hexadecimal value
// given below. we are gonna convert
// this from big Endian to little Endian
// and vice versa.
int big_Endian = 0x12345678;
int little_Endian = 0x78563412;
int result1, result2;
result1 = swap_Endians(big_Endian);
result2 = swap_Endians(little_Endian);
printf("big Endian to little:"
"0x%x\nlitle Endian to big: 0x%x\n",
result1, result2);
return 0;
}
// This code is contributed by SHUBHAMSINGH10 C
#include
// Function to swap a value from
// big Endian to little Endian and
// vice versa.
int swap_Endians(int value)
{
// This var holds the leftmost 8
// bits of the output.
int leftmost_byte;
// This holds the left middle
// 8 bits of the output
int left_middle_byle;
// This holds the right middle
// 8 bits of the output
int right_middle_byte;
// This holds the rightmost
// 8 bits of the output
int rightmost_byte;
// To store the result
// after conversion
int result;
// Get the rightmost 8 bits of the number
// by anding it 0x000000FF. since the last
// 8 bits are all ones, the result will be the
// rightmost 8 bits of the number. this will
// be converted into the leftmost 8 bits for the
// output (swapping)
leftmost_byte = (value & 0x000000FF) >> 0;
// Similarly, get the right middle and left
// middle 8 bits which will become
// the left_middle bits in the output
left_middle_byle = (value & 0x0000FF00) >> 8;
right_middle_byte = (value & 0x00FF0000) >> 16;
// Get the leftmost 8 bits which will be the
// rightmost 8 bits of the output
rightmost_byte = (value & 0xFF000000) >> 24;
// Left shift the 8 bits by 24
// so that it is shifted to the
// leftmost end
leftmost_byte <<= 24;
// Similarly, left shift by 16
// so that it is in the left_middle
// position. i.e, it starts at the
// 9th bit from the left and ends at the
// 16th bit from the left
left_middle_byle <<= 16;
right_middle_byte <<= 8;
// The rightmost bit stays as it is
// as it is in the correct position
rightmost_byte <<= 0;
// Result is the concatenation of all these values.
result = (leftmost_byte | left_middle_byle
| right_middle_byte | rightmost_byte);
return result;
}
// Driver Code
int main()
{
// Consider a hexadecimal value
// given below. we are gonna convert
// this from big Endian to little Endian
// and vice versa.
int big_Endian = 0x12345678;
int little_Endian = 0x78563412;
int result1, result2;
result1 = swap_Endians(big_Endian);
result2 = swap_Endians(little_Endian);
printf("big Endian to little: 0x%x\nlitle Endian to big: 0x%x\n",
result1, result2);
return 0;
} Java
// Java program to print the difference
// of Alternate Nodes
import java.util.*;
class GFG
{
// Function to swap a value from
// big Endian to little Endian and
// vice versa.
static int swap_Endians(int value)
{
// This var holds the leftmost 8
// bits of the output.
int leftmost_byte;
// This holds the left middle
// 8 bits of the output
int left_middle_byle;
// This holds the right middle
// 8 bits of the output
int right_middle_byte;
// This holds the rightmost
// 8 bits of the output
int rightmost_byte;
// To store the result
// after conversion
int result;
// Get the rightmost 8 bits of the number
// by anding it 0x000000FF. since the last
// 8 bits are all ones, the result will be the
// rightmost 8 bits of the number. this will
// be converted into the leftmost 8 bits for the
// output (swapping)
leftmost_byte = (value & 0x000000FF) >> 0;
// Similarly, get the right middle and left
// middle 8 bits which will become
// the left_middle bits in the output
left_middle_byle = (value & 0x0000FF00) >> 8;
right_middle_byte = (value & 0x00FF0000) >> 16;
// Get the leftmost 8 bits which will be the
// rightmost 8 bits of the output
rightmost_byte = (value & 0xFF000000) >> 24;
// Left shift the 8 bits by 24
// so that it is shifted to the
// leftmost end
leftmost_byte <<= 24;
// Similarly, left shift by 16
// so that it is in the left_middle
// position. i.e, it starts at the
// 9th bit from the left and ends at the
// 16th bit from the left
left_middle_byle <<= 16;
right_middle_byte <<= 8;
// The rightmost bit stays as it is
// as it is in the correct position
rightmost_byte <<= 0;
// Result is the concatenation of all these values.
result = (leftmost_byte | left_middle_byle |
right_middle_byte | rightmost_byte);
return result;
}
// Driver Code
public static void main(String[] args)
{
// Consider a hexadecimal value
// given below. we are gonna convert
// this from big Endian to little Endian
// and vice versa.
int big_Endian = 0x12345678;
int little_Endian = 0x78563412;
int result1, result2;
result1 = swap_Endians(big_Endian);
result2 = swap_Endians(little_Endian);
System.out.printf("big Endian to little: 0x%x\n" +
"litle Endian to big: 0x%x\n",
result1, result2);
}
}
// This code is contributed by PrinciRaj1992Python3
# Function to swap a value from
# big Endian to little Endian and
# vice versa.
def swap_Endians(value):
# Get the rightmost 8 bits of the number
# by anding it 0x000000FF. since the last
# 8 bits are all ones, the result will be the
# rightmost 8 bits of the number. this will
# be converted into the leftmost 8 bits for the
# output (swapping)
leftmost_byte = (value & eval('0x000000FF')) >> 0
# Similarly, get the right middle and left
# middle 8 bits which will become
# the left_middle bits in the output
left_middle_byle = (value & eval('0x0000FF00')) >> 8
right_middle_byte = (value & eval('0x00FF0000'))>> 16
# Get the leftmost 8 bits which will be the
# rightmost 8 bits of the output
rightmost_byte = (value & eval('0xFF000000'))>> 24
# Left shift the 8 bits by 24
# so that it is shifted to the
# leftmost end
leftmost_byte <<= 24
# Similarly, left shift by 16
# so that it is in the left_middle
# position. i.e, it starts at the
# 9th bit from the left and ends at the
# 16th bit from the left
left_middle_byle <<= 16
right_middle_byte <<= 8
# The rightmost bit stays as it is
# as it is in the correct position
rightmost_byte <<= 0
# Result is the concatenation of all these values
result = (leftmost_byte | left_middle_byle
| right_middle_byte | rightmost_byte)
return result
# main function
if __name__ == '__main__':
# Consider a hexadecimal value
# given below. we are gonna convert
# this from big Endian to little Endian
# and vice versa.
big_Endian = eval('0x12345678')
little_Endian = eval('0x78563412')
result1 = swap_Endians(big_Endian)
result2 = swap_Endians(little_Endian)
print("big Endian to little: % s\nlitle Endian
to big: % s" %(hex(result1), hex(result2)))C#
// C# program to print the difference
// of Alternate Nodes
using System;
class GFG
{
// Function to swap a value from
// big Endian to little Endian and
// vice versa.
static int swap_Endians(int value)
{
// This var holds the leftmost 8
// bits of the output.
int leftmost_byte;
// This holds the left middle
// 8 bits of the output
int left_middle_byle;
// This holds the right middle
// 8 bits of the output
int right_middle_byte;
// This holds the rightmost
// 8 bits of the output
int rightmost_byte;
// To store the result
// after conversion
int result;
// Get the rightmost 8 bits of the number
// by anding it 0x000000FF. since the last
// 8 bits are all ones, the result will be the
// rightmost 8 bits of the number. this will
// be converted into the leftmost 8 bits for the
// output (swapping)
leftmost_byte = (value & 0x000000FF) >> 0;
// Similarly, get the right middle and left
// middle 8 bits which will become
// the left_middle bits in the output
left_middle_byle = (value & 0x0000FF00) >> 8;
right_middle_byte = (value & 0x00FF0000) >> 16;
// Get the leftmost 8 bits which will be the
// rightmost 8 bits of the output
rightmost_byte = (int)(value & 0xFF000000) >> 24;
// Left shift the 8 bits by 24
// so that it is shifted to the
// leftmost end
leftmost_byte <<= 24;
// Similarly, left shift by 16
// so that it is in the left_middle
// position. i.e, it starts at the
// 9th bit from the left and ends at the
// 16th bit from the left
left_middle_byle <<= 16;
right_middle_byte <<= 8;
// The rightmost bit stays as it is
// as it is in the correct position
rightmost_byte <<= 0;
// Result is the concatenation of all these values.
result = (leftmost_byte | left_middle_byle |
right_middle_byte | rightmost_byte);
return result;
}
// Driver Code
public static void Main(String[] args)
{
// Consider a hexadecimal value
// given below. we are gonna convert
// this from big Endian to little Endian
// and vice versa.
int big_Endian = 0x12345678;
int little_Endian = 0x78563412;
int result1, result2;
result1 = swap_Endians(big_Endian);
result2 = swap_Endians(little_Endian);
Console.Write("big Endian to little: 0x{0:x}\n" +
"litle Endian to big: 0x{1:x}\n",
result1, result2);
}
}
// This code is contributed by Rajput-Ji输出：
big Endian to little: 0x78563412
litle Endian to big: 0x12345678