An example of C consortium union

An example of union in C

1. Definition:

union(int i, short s, char c) un; 
un.i = 3; 
printf( " i=%d " ,un.i); 
printf( " length = %d\n " ,sizeof(un);//==4 , has the largest variable to determine 

2. Equivalent to List T in java

3. Data exchange

void swap(int *p , int *q){ 
int temp = *p; 
*p = *q; 
*q = temp; 
}

4. Print the address

int i = 2; 
printf( " %#x " ,&i);

5. Pointer prints array values

int arr[] = {1,2,3,4}; 
int *p = &arr; 
prinft( " %d\n " , *(p+0)); 
prinft( " %d\n " , *(p+1));

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