The second practice

JavaScript programming problem

The return value of the following two functions are the same as you? why?

function foo1() {
    return {
        bar: "hello"
    };
}

function foo2() {
    return
    {
        bar: "hello"
    };
}

In programming languages, basically a semicolon (;) separated from the statement, which may increase the readability of the code and cleanliness. In the JS, should a separate line in half and statements, statements can often be omitted semicolons (;), JS parser to decide whether to automatically fill semicolon normal compilation according to whether:

var test = 1 + 2；
console.log(test); //3

In the above case, in order to correctly parsing code, will not be automatically filled with a semicolon, but to return, break, continue other statement is followed by wrapping, the parser will automatically fill in behind the semicolon (;), so the above second function this becomes:

function foo2() {
    return;
    {
        bar: "hello"
    };
}

So the second function is to return undefined.

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MySQL programming problems

With a SQL statement, check out the name of the student in every subject is greater than 80 points.

Table name student_score

name	course	score
Joe Smith	Chinese	81
Joe Smith	mathematics	75
John Doe	Chinese	76
John Doe	mathematics	90
Wang Wu	Chinese	81
Wang Wu	mathematics	100
Wang Wu	English	90

SELECT DISTINCT name FROM student_score
WHERE name NOT IN (SELECT DISTINCT name FROM student_score WHERE score<=80);

or

SELECT name FROM student_score GROUP BY name HAVING MIN(score)>80;

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Java programming problem

Ball free fall from a height of 100 meters, the anti-jump back after each landing half its original height; down again, find it at the 10th floor, after a total of how many meters? 10th rebound tall?

Package Test; 

public  class Test2 {
     / ** 
     * 
     * @param H from 
     * @param n times 
     * @return rebound height of the n-th
      * / 
    public  static  Double sumBallHeight ( Double H, int n) {
         IF (n ==. 1 )
             return H / 2 ;
         the else 
            return sumBallHeight (H / 2, n--. 1 ); 
    } 

    public  static  void main (String [] args) {
        System.out.println (sumBallHeight ( 100, 10 )); 
    } 
} 

Package Test; 

public  class term TI2 { 

    public  static  void sumBallHeight ( int initHeight, int Times) {
         // the number of meters after landing 
        Double SUM = 0 ;
         // rebound height 
        Double height = 0 ;
         for ( int I =. 1; I <= Times; I ++ ) {
             IF (I ==. 1 ) { 
                height   = initHeight / 2 ;
                SUM + = initHeight;
            } The else { 
                SUM = SUM + height * 2 ; 
                height = height / 2 ; 
            } 
        } 
        System.out.println ( "first" + times + "landing times when, after a total of" + sum + "m" ); 
        the System.out .println ( "first" + times + "rally" + height + "m" ); 
    } 

    public  static  void main (String [] args) { 
        sumBallHeight ( 100,. 3 ); 
    } 
}