This is their pseudocode for bubble sort: -------------------------------------------------------

Repeat n-1 times
For i from 0 to n–2
If numbers[i] and numbers[i+1] out of order
Swap them
If no swaps
Quit

------------------------------------------------------- Then, David Malan supposedly analyzed the running time by multiplying n-1 by n-2.

I am taking Harvard's CS50 class. We are learning C. They use their own library where you include cs50.h. There is a function called get_string that returns a string. I think it has a memory leak. I think this is the source code: https://github.com/cs50/libcs50/blob/main/src/cs50.c They are saying stuff like: string name = get_string("What is your name?"); Then, they never call free on the memory in main. Anyone know how the memory gets freed or if it is a leak? Thanks.

Can someone explain to me in layman's terms how this function works? https://codebrowser.dev/glibc/glibc/string/strlen.c.html Thank you.

Let's say you need to find the top 100 best-selling books out of a list of a million books. What is the appropriate algorithm? I thought it would be QuickSelect, but that only chooses one item. Thank you.

Let's say you have a table with an index on the field "username". Is it true that eventually you'll have some really time-consuming inserts when the hash table has to resize itself? Hash table resize is O(n), I think. Thanks.

I don't see a forum for assembly. Can you create such a forum? Thanks.

I was looking at the documentation for CREATE INDEX in SQL: https://www.w3schools.com/sql/sql_create_index.asp

CREATE INDEX index_name
ON table_name (column1, column2, ...);

I don't understand when you would create it for multiple columns. Let's say you did this:

CREATE INDEX idx_pname ON Persons (LastName, FirstName);

Does that create one index on two columns? Or, is that the same as creating two indexes? For instance, does that statement create two hashtables? Or one hashtable? Thank you.

Let's say you have a SQL database with a table called USERS. Let's say it has 500,000 users in it. Let's say you do this:

SELECT PASSWORD FROM USERS WHERE USER='bill.gates';

Let's say there's no indices on the table. Does the database just do a linear search thru each user? Thank you.

Let's say you don't want to use a SQL database, but you want to create a user data system for a web-based e-mail service. You want to store the following data about each user: username password address alternate email address phone number What kind of data structure should you use? Thank you.

How do you separate large numbers in Java? I want to use something like commas. I think this works in C++, but it doesn't work in Java:

int onebillion = 1'000'000'000;

Anyone know? Thanks.

Are you saying that passing 0 doesn't return undefined? Thanks.

For doubles, I believe there is a positive zero and a negative zero.

I am trying to help a lass with her JavaScript code. Take a look at this image she posted: https://pbs.twimg.com/media/GDpFl1SWcAA0jk1?format=jpg&name=small[^] She claims the blue lines next to console.log are the output. Does it make sense to you?

Does anyone know what happens if you pass 0 to this function? https://pbs.twimg.com/media/GDh5G70XcAAyqTv?format=jpg&name=small Thank you.

I am in IntelliJ IDEA. I want to view the disassembly of this code to see if it does two comparisons:

if (-0.0 == 0.0) System.out.println("they're equal");

Based on searching, it sounds like IntelliJ can't do that. Anyone know of a Java IDE that can do this? Thank you.

The class is right here: https://www.edx.org/learn/computer-programming/iitbombay-programming-basics Here is some code from the class:

int main()
{
int numStudents;
int * A;
cin >> numStudents;
A = new int[numStudents];
if (A != NULL) { A[0] = 10; A[1] = 15;}
return 0;
}

If a memory allocation with new fails in C++, should it return NULL or throw an exception? I have this code:

#include
#include
#include
using namespace std;

int main() {
try{
char *p = new char[44'321'833'923];

 if (!p) {
    cout << "memory allocation failed";
    exit(1);
    
}

}
catch(exception&e)
{
    cout << "caught it." << e.what();
    exit(1);
}
catch (...)
{
    cout << "caught exception;";
    exit(1);
}


return 0;

}

The class I'm taking says it returns NULL, but the code seems to throw an exception. Anyone know? Thanks.

I am trying to catch a divide-by-zero error with the following code:

#include
using namespace std;

int main() {
try {
int a = 0;
int x = 5 / a;
}
catch (exception e)
{
cout << e.what() << endl;
}
catch (...)
{
cout << "caught ..." << endl;
}

}

For some reason, neither of my catch blocks gets executed. Anyone know how to catch the exception? Thank you.

Interesting. I tried doing a "Step Into" on that line in the debugger, but it won't go to it. If I do a "Go to Definition", it goes to this in xiosbase:

\_NODISCARD bool \_\_CLR\_OR\_THIS\_CALL operator!() const noexcept /\* strengthened \*/ {
    return fail();
}

However, I put a breakpoint there, and it doesn't break.

I have the following file code:

#include
#include
using namespace std;

int main() {

//add code below this line

string path = "student/text/readpractice.txt";

try {
    ifstream file;
    file.open(path); //content of file goes into memory buffer
    if (!file) {
        throw runtime\_error("File failed to open.");
    }
    cout << file.rdbuf(); //read the buffered content
    file.close();
}

catch (exception& e) {
    cerr << e.what() << endl;
}

//add code above this line

return 0;

}

Can someone help me understand how this line works:

if (!file) {

How can you use the exclamation point operator on what is probably a class? Is there some type of overloading that has occurred? I looked thru the code, and I couldn't find the ! point being overloaded. Any ideas? Thanks.