Two methods to determine the machine size

Method 1

Idea: Use Pointer to force type conversion

Copy codeThe Code is as follows: # include <stdio. h>
Int main (void)
{
Int data1 = 0x12345678;
Int I;
For (I = 0; I <4; I ++)
{
Printf ("% # x -----> % p \ n", * (char *) & data1 + I), (char *) & data1 + I );
}
Return 0;
}

From the output results, we can see that the high address 0xbfc1b1ff stores 0x12 of the data, and the low address 0xbfc1b1fc stores 0x78 of the data. Therefore, it is a small client. We can also see that the data address actually points to the space for storing low-level data.

Method 2

Idea: Use the shared body to store all data from the same address.

Copy codeThe Code is as follows: # include <stdio. h>

Int main (void)

{

Int I;

Union endian

{

Int data;

Char ch;

} Test;

Test. data = 0x12345678;

If (test. ch = 0x78)

{

Printf ("little endian! \ N ");

}

Else

{

Printf ("big endian! \ N ");

}

For (I = 0; I <4; I ++)

{

Printf ("% # x ------- % p \ n", * (char *) & test. data + I), (char *) & test. data + I );

}

Return 0;

}