wukaihua119

#include <stdio.h> 
#include <stdint.h> 
#include <string.h> 
#include <stdlib.h> 

#include <errno.h> 
#include <fcntl.h> 
#include <sys/stat.h> 
#include <sys/types.h> 
#include <unistd.h> 

wukaihua119

// using mask to convert the integer to binary. 
void printBin( int num ){ 
    int mask = 1 << 7; // 10000000 
    for( int i = 0; i < 8; ++i ){ 
        printf( "%d", ((( num & mask ) == 0 )? 0:1) ); 
        mask >>= 1; 
    } 
    printf( "\n" ); 
} 

wukaihua119

#include<iostream> 
#include<cstdio> 

struct a{ 
    int val; 
}; 

int main(){ 

    /* Pointer's calculation: 

wukaihua119

#include"avl.h" 
#include<algorithm> 

namespace Tree{ 

    // constructor 
    AVLTree::AVLTree( void ){ } 
    // destructor 
    AVLTree::~AVLTree( void ){
        this->TreeDestory( this->root ); 

wukaihua119

1. GROUP_CONCAT() 
   SELECT GROUP_CONCAT( <cols> [ SEPARATOR <"char"> ] ) FROM <table>; 
   SELECT GROUP_CONCAT( <cols> [ SEPARATOR <"char"> ] [ ORDER BY <cols>] ) FROM <table>; 


2. GROUP BY vs ORDER BY 
   **ORDER BY** alters the order in which items are returned. 
   **GROUP BY** is used to organize results according to the structure of the data returned. 
   The results are indexed alphabtically. 
   ```GROUP BY``` is defined as a way of aggregating records by the specified columns which allow you to perform aggregation functions on non-grouped columns

wukaihua119

package Thirty; 

import java.util.Arrays; 
import java.util.ArrayList; 
import java.util.List; 

public class Main{ 

    public static void main( String [] args ){