I have noticed on several occasions that I may be creating a problem (described below) when I lay my C++ code out as below. While it may not be ideal, I do it to save space sometimes.
I can only show you a small code snipped because the program is quiet large. Hopefully can articulate the problem clearly.
string st= "TestString,"; // I declare a string.
//further down in my code I want to remove the comma as I do below.
// I do it in the below syntax to save space. Ok, maybe not ideal but I did it.
if(st[st.length()-1]==','){st=st.substr(0,st.length()-1);}
cout << "My new string is: " << st << endl;
// I place a line of codeimmediately below my if statement.
The problem is, sometimes the code directly below my one line If Statement follows the logic of the If Statement when I thought that would be reserved for the code only int the { } .
It doesn't always happen but it does happen randomly. When I leave a space between the One Line If Statement and the code below it, the problem goes away.
Is there a common problem I have created here or is this just an unusual anomaly?
Related
I am currently stuck in this problem that I do not have any idea to fix. It is regarding a previous question that I have asked here before. But I will reiterate again as I found out the problem but have no idea to fix it.
My program accesses a text file that is updated constantly every millisecond 24/7. It grabs the data line by line and does comparison on each of the line. If any thing is "amiss"(defined by me), then I log that data into a .csv file. This program can be run at timed intervals(user defined).
My problem is that this program works perfectly fine on my computer but yet it doesnt on my clients computer. I have debug the program and these are my findings. Below is my code that I have reduced as much possible to ease the explanation process
int result;
char ReadLogLine[100000] = "";
FILE *readLOG_fp;
CString LogPathName;
LogPathName = Source_Folder + "\\serco.log"; //Source_Folder is found in a .ini file. Value is C:\\phython25\\xyratex\\serco_logs
readLOG_fp = fopen(LogPathName, "r+t");
while ((result = fscanf(readLOG_fp, "%[^\n]\n", ReadLogLine)) != EOF) // Loops through the file till it reaches the end of file
{
Sort_Array(); // Here is a function to sort the different lines that I grabbed from the text file
Comp_State(); // I compare the lines here and store them into an array to be printed out
}
fclose(readLOG_fp);
GenerateCSV(); // This is my function to generate the csv and print everything out
In Sort_Array(), I sort the lines that I grab from the text file as they could be of different nature. For example,
CStringArray LineType_A, LineType_B, LineTypeC, LineTypeD;
if (ReadLogLine == "Example line a")
{
LineType_A.add(ReadLogLine);
}
else if (ReadLogLine == "Example line b")
{
LineType_B.add(ReadLogLine);
}
and so on.
In CompState(), I compare the different values within each LineType array to see if there are any difference. If it is different, then I store them into a seperate array to print. A simple example would be.
CStringArray PrintCSV_Array;
for (int i = 0; i <= LineType_A.GetUpperBound(); i++)
{
if (LineType_A.GetAt(0) == LineType_A.GetAt(1))
{
LineType_A.RemoveAt(0);
}
else
{
LineType_A.RemoveAt(0);
PrintCSV_Array.Add(LineType_A.GetAt(0);
}
}
This way I dont have an infinite amount of data in the array.
Now to the GenerateCSV function, it is just a normal function where I create a .csv file and print whatever I have in the PrintCSV_Array.
Now to the problem. In my client's computer, it seems to not print anything out to the CSV. I debugged the program and found out that it keeps failing here.
while ((result = fscanf(readLOG_fp, "%[^\n]\n", ReadLogLine)) != EOF) // Loops through the file till it reaches the end of file
{
Sort_Array(); // Here is a function to sort the different lines that I grabbed from the text file
Comp_State(); // I compare the lines here and store them into an array to be printed out
}
fclose(readLOG_fp);
It goes into the while loop fine as I did some error checking there in the actual program. The moment it goes into the while loop it breaks out of it suggesting to me it reach EOF for some reason. When that happens, the program has no chance to go into both the Sort_Array and Comp_State functions thus giving me a blank PrintCSV_Array and nothing to print out.
Things that I have checked is that
I definitely have access to the text file.
My thoughts were because the text file is updated every
millisecond, it may have been opened by the other program to write
into it and thus not giving me access OR the text file is always in
an fopen state therefore not saving any data in for me to read. I
tested this out and the program has value added in as I see the KB's
adding up in front of my eyes.
I tried to copy the text file and paste it somewhere else for my
program to read, this way I definitely have full access to it and
once I am done with it, Ill delete it. This gave me nothing to print
aswell.
Am I right to deduce that it is always giving me EOF thus this is
having problems.
while ((result = fscanf(readLOG_fp, "%[^\n]\n", ReadLogLine)) != EOF) // Loops through the file till it reaches the end of file
If yes, How do I fix this?? What other ways can I make it read every line. I have seriously exhausted all my ideas on this problem and need some help in this.
Thanks everyone for your help.
Error is very obvious ... you might have over looked it..
You forgot to open the file.
FILE *readLOG_fp;
CString LogPathName;
LogPathName = Source_Folder + "\\serco.log";
readLOG_fp = fopen(LogPathName.GetBuffer());
if(readLOG_fp==NULL)
cout<<"Error: opening file\n";
I am trying to write a function in my program that loads a huge text-file of 216,555 words and put them as strings into a set. This works properly, but as expected, it will hang for a few micro seconds while looping through the file. But there is something funky going on with my loop, and it's not behaving properly. Please take the time to read, I am sure there's a valid reason for this, but I have no idea what to search for.
The code, which is working by the way, is this:
ifstream dictionary;
dictionary.open("Dictionary.txt");
if(dictionary.fail())
{
cout<<"Could not find Dictionary.txt. Exiting."<<endl;
exit(0);
}
int i = 0;
int progress = 216555/50;
cout<<"Loading dictionary..."<<endl;
cout<<"< >"<<endl;
cout<<"<";
for(string line; getline(dictionary, line);)
{
usleep(1); //Explanation below (not the hangtime)
i++;
if(i%progress == 0)
cout<<"=";
words.insert(line);
}
The for-loop gets every string from the file, and inserts them in the map.
This is a console-application, and I want the user to see the progress. It's not much of a delay, but I wanted to do it anyway. If you don't understand the code, I'll try to explain.
When the program starts, it first prints out "Loading Dictionary...", and then a "<" and a ">" separated by 50 spaces. Then on the next line: "<" followed by a "=" for every 433 word it loops through (216555/50). The purpose of this is so the user can see the progress. The wanted output half way through the loop would be like this:
Loading dictionary...
< >
<=========================
My problem is:
The correct output is shown, but not at the expected time. It prints out the full progress bar, but that only after it has hanged and are done with the loop. How is that possible? The correct number of '=' are shown, but they all pop out at the same time, AFTER it hangs for some microseconds. I added the usleep(1) to make the hangtime a bit longer, but the same thing happened. The if-statement clearly works, or the '=' would've never showed at all, but it feels like my program is stacking the cout-calls for after the entire loop.
The weirdest thing of all, is that the last cout<<"<"; before the for-loop starts, is also shown at the same time as the rest of its line; after the loop is finished. Why and how?
You never flush the stream, so the output just goes into a buffer.
Change cout<<"="; to cout<<"="<<std::flush;
You need to flush the output stream.
cout << "=" << std::flush;
The program is "stacking the cout-calls". It's called output buffering, and every major operating system does it.
When in interactive mode (as your program is intended to be used), output is buffered by line; that is, it will be forced to the terminal when a newline is seen. You can also have block-buffered (fixed number of bytes between forced outputs; used when piping output) and unbuffered.
C++ provides the std::flush stream modifier to force an output at any point. It can be used like this:
cout << "=" << std::flush;
This will slow down your program a bit; the point of buffering is for efficiency. As you'll only be doing it about 51 times, though, the slowdown should be negligible.
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 have a function that creates and insert some numbers in a vector.
if(Enemy2.dEnemy==true)
{
pt.y=4;
pt.x=90;
pt2.y=4;
pt2.x=125;
for(int i=0; i<6; i++)
{
Enemy2.vS1Enemy.push_back(pt);
Enemy2.vS2Enemy.push_back(pt2);
y-=70;
pt.y=y;
pt2.y=y;
}
Enemy2.dEnemy=false;
Enemy3.cEnemy=0;
}
It should insert 6 numbers in two vectors, the only problem is that it doesn't - it actually inserts more.
I don't think the snippet will run unless Enemy2.dEnemy == true, and it won't stay true for ever.
The first time the snippet runs, then Enemy2.dEnemy is set to false and it shouldn't run again.
I don't set Enemy2.dEnemy to true anywhere except when the window is created.
If I insert a break point any where in the snippet, the program will work fine - it will insert ONLY 6 numbers in the two vectors.
Any ideas what's wrong here?
ok so i did some debugging.
i found that Enemy2.dEnemy=false; is being skipped for some reason.
i tried to do this to see if it was.
if(Enemy2.dEnemy)
{
pt.y=4;
pt.x=90;
pt2.y=4;
pt2.x=125;
for(int i=0; i<6; i++)
{
Enemy2.vS1Enemy.push_back(pt);
Enemy2.vS2Enemy.push_back(pt2);
y-=70;
pt.y=y;
pt2.y=y;
}
TCHAR s[244];
Enemy2.dEnemy=false;
if(Enemy2.dEnemy)
{
MessageBox(hWnd, _T("0"), _T(""), MB_OK);
}
else
{
MessageBox(hWnd, _T("1"), _T(""), MB_OK);
}
Enemy3.cEnemy=0;
}
well the message box popped saying 1 and my code worked fine. it seems that Enemy2.dEnemy=false; doesn't have time to run ;/
blahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblah!
ok i found where is the real problem which was causing to insert more than 6 numbers..
it was where i was asigning Enemy2.dEnemy=true;
if(Enemy2.e1)
{
Enemy2.now=time(NULL);
Enemy2.tEnemy=Enemy2.now+4;
Enemy2.e1=false;
}
if(Enemy2.tEnemy==time(NULL))
{
check=1;
Enemy2.aEnemy=0;
Enemy2.dEnemy=true;
}
the problem seems that the second if runs more than one time, which is weird!
First things first: get rid of that abominable if (Enemy2.dEnemy == true) - it should be:
if (Enemy2.dEnemy)
(I also prefer to name my booleans as a readable sentence segments like Enemy2.isABerserker or Enemy3.hasHadLeftLegCutOffThreeInchesBelowTheKnee but that's just personal preference).
Other than that, the only thing I can suggest is a threading problem. There's nothing wrong with that code per se, but there is a window in which two threads could enter the if statement and both start pushing values into your vector.
In other words, if thread 1 is doing the pushing when thread 2 encounters the if statement, thread 2 will also start pushing values, since thread 1 has yet to set dEnemy to true. And don't think you can just move the assignment to the top of the if block - that will reduce but not remove the window.
My advice is to print out the contents of the vectors in the situation where they have more than six entries and that may give a clue as to what's happened (post the output here if you wish).
Re your update that the second if below is running twice:
if(Enemy2.e1)
{
Enemy2.now=time(NULL);
Enemy2.tEnemy=Enemy2.now+4;
Enemy2.e1=false;
}
if(Enemy2.tEnemy==time(NULL))
{
check=1;
Enemy2.aEnemy=0;
Enemy2.dEnemy=true;
}
If this code is executed twice in the same second (and that's not beyond the bounds of possibility), the second if statement will run twice.
That's because time(NULL) give you the number of seconds since the epoch so, until that second is over, you may well be executing the contents of that if thousands of times (or more).
If this problem disappears when you put in a breakpoint or a diagnostic output message, that's a strong clue that the problem is undefined behavior, which is usually caused by something like dereferencing an uninitialized pointer or careless use of const_cast.
The cause of the problem probably has nothing to do with the code you're looking at. It's caused somewhere else and just happens to show up here. It's like someone being hit by a falling brick: the obvious symptom is a man lying unconscious on the sidewalk, but the real problem has nothing to do with the man or the sidewalk, it's several stories up.
If you want to find the cause of the error, remove your diagnostics until the problem reappears, then start removing everything else. Prune away all of the other code. Whenever the error stops, back up until it starts again; if you don't see the cause of the error, start pruning somewhere else. Eventually the bug will have nowhere to hide.
One of my functions returns a 'msg' object... which is merely a string.
I got into 2 for loops in the function.
msg=''
for e in example:
msg+= "some crap"
msg+= "some crap1"
for sl in somelist
msg+= v.somevalue
msg+="-------------"
return httpresponse(msg)
There's an example of the code.
'somelist' contains two values... when the 'msg' returns it only returns the second of the two values! I'm rather confused.
Your code uses sl as the loop variable, then pulls values from v. I'm not sure how they relate. If the final message includes a number of copies of the last value, then probably you forgot to relate sl and v somehow. If it includes only a single copy of the last value, then perhaps the line of code appending to msg is actually outside the loop. This would mean nothing is appended as the loop progresses, then once it exits, the last value is appended.
If your code is exactly like that, it should work just like you want it to. However, as this clearly isn't the actual code, I'd guess you have msg = ... somewhere, when you should have msg += ... At least that's the most likely reason for the behaviour you're seeing.
If you have trouble finding where it goes wrong, put in there some "print msg" statements and test it by running your Django project in development server. You'll see where it goes wrong.