I have been given a homework but don't know how to write some part of it explained as following:
..."In addition make sure your program keeps running until the user enters “quit”. To keep your program running you should use “for” statements. However, for statements doesn’t provide your program to run to infinity. Therefore, for your range value, give the maximum value that your OS can handle. For example; if you are using a 32 bit OS and interpreter, your computer should use 2^31 as the maximum value. "
What did our teacher mean do you think?(PYTHON 2.7)
You have to make mention about the language.
Java program:
do {
//Show information
//Execute preliminar code
//Here you can get the Exit command
} while (Exit command is true);
Hope this helps!
Maybe you could write a code that consistently asks the user for an input. For example:
number = int(input("Enter integer less than 5: "))
while number>5:
print("Try again")
number = int(input("enter integer number"))
if number == quit:
break
If I did this correctly, this program will continue until one of two conditions is met, 1) you enter a number less than five OR 2) you enter the word quit
As I learned later,we were supposed to use
for i in range(2**31):
#Your program codes apart from function definitions are here.
.
string=raw_input("Enter quit to exit.")
if (string == "quit"):
break
Related
I'm working on a QT project where a user inputs their full name and the program generates a random 5 character password based off of the letters in their name. Unfortunate I've run into an issue where it works but every time I rerun the program it yields the same result. So it clearly isn't very random. Even after exiting QT Creator and opening it again and running the program with the same user input it yields the same results.
I also am required to generate the password without spaces.
Here is my code:
while(password.length() < 5) {
int index = qrand() % fullName.length();
QChar nextChar = fullName.at(index);
if (!nextChar.isSpace()) {
password.append(nextChar);
}
}
Any solution would be much appreciated.
You need to provide qrand with a suitable seed (usually at program startup). Try:
QTime now= QTime::currentTime() ;
qsrand( now.msec() );
You don't ask about this, but are you checking that fullName's length is not zero (as the program would attempt to divide by zero)? Or that it's not composed of blanks only (as it would loop forever)? A simple solution to both is to trim fullName and check that its length is strictly greater than zero.
Referring to two questions:
Incorrect output from C++ Primer 1.4.4
Confused by control flow execution in C++ Primer example
My question is answered in both of those posts, but I want to delve further.
First, I know this is only the beginning, but let's say I make a fully functional program that runs in a designed window. By that level, will I already know how to implement a EOF? I can't expect someone running my program to know that they need to hit Control-Z.
Is there a way to implement a specific code that functions so that it does not need me to type in an unrecognized value?
Also one guy in those questions somewhat answered the importance of EOF, but how come the program doesn't even post the final cnt - 1?
Let's say I do the numbers 10 10 10 20 20 20. Without EOF, this will only show the "10 repeats 3 times." How come the program doesn't at least type in the count "10 repeats 3 times and 20 repeats 2 times" minus the final one with white space?
lets say I make a fully functional program that runs in a designed window. By that level, will I already know how to implement a eof? I can't expect someone running my program to know that they need to hit ctrl + z.
You could either tell the user explicitly to do a specific action to end input or the design of the window itself could tell the user the information implicitly. For instance, a dialog box could ask the user to enter input and click an OK button when done.
Is there a way to implement a specific code that functions so that it does not need me to type in an unrecognized value?
It seems like you would rather use a newline character to terminate your input. An example of this usage could be std::getline. Instead of writing
while (std::cin >> val)
you could instead use
std::string line;
if (std::getline(std::cin,line))
and assume that your user's input only consists of one line of values. There are plenty of other ways to similarly achieve this task depending on how you want to constrain the user's input.
Let's say I do the numbers 10 10 10 20 20 20. WIthout eof this will only show the "10 repeats 3 times." How come the program doesn't at least type in the count "10 repeats 3 times and 20 repeats 2 times" minus the final one with white space?
Without the eof your program is still executing the while (std::cin >> val) loop since std::cin >> val has not yet received invalid input.
Since the line
std::cout << currVal << " occurs " << cnt << " times" << std::endl;
occurs after that while loop finishes execution, you don't (yet) see any information about the three 20's in the input.
When you are reading a sequence of inputs you'll need some indication when your down. That could be a sentinel value ("enter 999 to stop reading"; you'd need to detect that while reading), an invalid input ("enter X to stop reading"; when reading an int the value X is illegal and causes the stream to got into failure mode, i.e., have std::ios_base::failbit set), or the more conventional "there isn't anything more to read". For a file, the last conditions is straight forward. When reading data from the console you'll either need to teach people how to terminate the input or you'll need to use a different approach.
If you want to intercept any keypressed and react on them directly you may do so, too. You could, e.g., use ncurses and control your input via that. You could also set the concole to non-buffering (on POSIX systems using tcgetattr() and tcsetattr() to clear the ICANON flag) and deal directly with all key presses to decide whether you want to continue reading or not.
Although I'm certainly up to doing fancy I/O stuff I normally don't bother: users will understand the "end of input" character and just deal with it. That is, my input normally looks something like this:
while (in >> whatever_needs_to_be_read) { ... }
... or, if the input is genuinely line oriented
for (std::string line; std::getline(in, line); ) { ... }
The function doing this input will then be called with a suitable std::istream which may be std::cin although I have typically some way to also read from a file (in addition to the shell-privided input redirection).
BTW, despite some indications in the questions referenced, "EOF" is not a character being read. It is a character entered, though (normally). ... and it is quite conventional to "know" the end of input character (on POSIX systems a ctrl-D and on Windows a ctrl-Z). You can use other indicators, e.g., the "interrupt" (ctrl-C) but that takes more work and doesn't integrate nicely with stream. To use the interrupt chacter you'd need to setup a signal handler for SIGINT and deal with that. One slightly annoying part of doing so is that if you get it wrong you'll need to find a different way to kill the program (e.g. on POSIX using ctrl-Z to put the process to sleep and kill it via a harsher signal).
So I'm working on a simple little text-based game in D to gain some experience working with the language. Here is a do-while loop that I'm currently struggling with:
do{
writeln("a. Advance 1 year\tc. Advance 10 years\tq. Quit");
writeln("b. Advance 5 years\td. Modify faction");
input = chomp(stdin.readln());
switch(input){
...
default:
break;
}
writeln(input[0]);
}while(input[0] != 'q');
Now the problem I'm running into is that when I hit q and enter the loop doesn't exit. It just keeps going. But then after the first time q is input, another q will terminate the loop. The writeln is in there as a sanity check, and it prints out the characters I type in exactly as typed. I feel like I'm going crazy, but it's probably just a simple type-o or something you guys will spot instantly. Nothing in the switch statement modifies 'input'.
EDIT: Okay some people have been asking to see all of the code. Here it is: http://pastebin.com/A7qM5nGW
When I said nothing in the switch modified input, it was to hide the fact I hadn't written anything in the switch yet. I've been trying to get the quit part to work right before adding the more complicated stuff. Also, here's a sample file for what I run it on: http://pastebin.com/4c2f4Z5N
Okay my friend found it. It has nothing to do with the while loop itself. I briefly forgot that args[0] is the name of the program. So it's actually running through the parent loop once with nothing, then actually quitting, and then running through the appropriate loop. It was fixed by making the parent loop like so...
foreach(filename; args[1..$]){
...
do{
...
while(input[0] != 'q');
}
as opposed to:
foreach(filename; args){
etc...
Yeah. So, I'm trying to make a code for a guessing game. In this game, there's a hard mode. In hard mode, you have 15 guesses, and have to guess between 1 and 500. But my problem is this:
I'm trying to have hard mode save & display your wins/losses, but when it outputs the contents of wins.txt it outputs something like this:
Wins: 0x7fffee26df78
Losses: 0x7fffee26e178
It's really confusing me. Here's the part of the code I have for that:
ifstream losses_var("losses.txt");
ifstream wins_var("wins.txt");
losses_var>> loss;
wins_var>> win;
wins_var.close();
losses_var.close();
Then it gets called with:
cout<<"Wins: "<< wins <<"\nLosses: "<< losses <<"\n"
If you would like to see the full source code, it's here: http://pastebin.com/gPT37uBJ
My second problem:
Hard mode won't display when you win. That's pretty much the whole problem. In my code, the loop for asking users for input uses
while (guess != randNum)
So at the end bracket I have what I want the code to display when a user wins, but it just doesn't run. It just stops. I would like it if someone could help me with this. The line that has the bug is line 97 through 105. Again, source code is here: http://pastebin.com/gPT37uBJ
You've got your variable names confused
cout<<"Wins: "<< wins <<"\nLosses: "<< losses <<"\n";
should be
cout<<"Wins: "<< win <<"\nLosses: "<< loss <<"\n";
It's important to pick good variable names. One reason is so that you don't confuse yourself about what your variables mean (if you confuse yourself think how it's going to be for someone else looking at your code).
Others have already answered the output problem (win vs. wins). The other problem is probably in your logic of while loop nesting. The outer loop (while (guess != randNum)) starts, but its body contains the entire inner loop (while (guesses_left != 0)). This means that the outer condition is not checked again until the inner loop terminates, which means you've run out of guesses. Also note that if you guess correctly, inner loop will never terminate. You probably want something like this:
while (guesses_left > 0) {
// input user's guess
if (guess < randNum) {
// process it
} else if (guess > randNum) {
// process it
} else {
// it's equal, user won
// do what's necessary for a win
return 0;
}
}
// ran out of guesses
// do what's necessary for a loss
return 0;
You are not writing your variables win and loss to cout. From your pasted code, I can see that wins and losses are ofstream objects, which means you are probably seeing addresses there. I would advise you to choose more informative variable names to avoid hard to spot mistakes like this.
I need help here I wrote code for my lab that "The loop will iterate a total of 10 times using the value of a variable that is incremented by one each time the loop completes."strong text but when I run my python file by click just open it refuse to run in command prompt...When I test in Edit with IDLE it runs fine...I can't figure out why it wont run...
here is what I wrote for my code:
counter = 0
while counter < 10:
counter = counter + 1
print counter
print "the loop is finished"
Perhaps it's just done way too fast.
Have you tried adding a raw_input() at the bottom of the file?
It looks like you have indentation errors (mainly with the print statements being indented one space further than the code above them).
Does this work for you:
counter = 0
while counter < 10:
counter = counter + 1
print counter
print "the loop is finished"
Python has strict indentation rules, if you want to learn more about them I would suggest reading this wikipedia page, it's pretty good.