I am working with dirEntries. Great function by the way. I wanted to test for the number of files before I used a foreach on it. I looked here on stack overflow and the suggested method was to use the walkLength function (Count files in directory with Dlang). I took that suggestion. The return from it was a non-zero value - great. However, the foreach will not iterate over the result of dirEntries. It acts like the walkLength has left the dirEntries at the end of the range. Is there a way to reset it so I can start at the beginning of the dirEntries list? Here is some example code:
auto dFiles = dirEntries("",filter, SpanMode.shallow);
if (walkLength(dFiles) > 0)
{
writeln("Passed walkLength function");
foreach (src; dFiles)
{
writeln("Inside foreach");
}
}
The output shows it gets past the walkLength function, but never gets inside the foreach iterator.
Am I using dirEntries wrong? I have looked at Ali Cehreli's great book Programming in D as someone suggest. Nothing stuck out at me. I have looked online and nothing points to my interpretation of the problem. Of course, I could be completely off base on what the problem really is.
dirEntries gives you a range. You consume that range with walkLength and reach its end. Then you attempt to read more entries from it with the foreach loop. However, you have already reached its end, so there is nothing more to read.
You can either repeat the dirEntries call, use the array function from std.array to convert the range to an array, or use the .save function to create a copy of the range that you pass to walkLength.
If you don't care about the length and only care about whether it's empty, you can use the .empty property of the range instead of walkLength.
Related
Hello I have been having trouble with my program I've created a list and I have the following program
Its goal is to Read the 5 variables inside the text file 5 variables in 5 different inputs
so I manage to correctly show the list inside the while loop since every time a line is read it's printed untill .eof(End Of File)
My goal is that I am trying to print the list OUTSIDE of the while Loop that has already read and printed those 5 variables 10x the problem is that it repeats the last entered 5 Variables in the list
I and repeats that 10x (size of the list)
I've also tried something like this inside the for loop which I found in here:
int ID=it->ID;
string NAME=it->NAME;
int SEMESTER=it->SEMESTER;
string DIRECTION=it->DIRECTION;
double GRADE=it->GRADE;
As if those are nodes but I am a starter with nodes as well as lists and it seems to have failed
When I look at the code you've provided, I see that in your for loop the a_student is used, which is not updated by/with the iterator. Basically you're not looping over the created student list.
Maybe try using std::for_each (cppreference) it will save you a lot of time:)
Godbolt example: https://godbolt.org/z/fQUhcr
The issue on the left column of code is that you are not de-referencing the iterator. You never set the a_students variable inside the loop, so why do you expect it to change on each iteration?
Write something like:
a_students = *it;
inside the loop. However there is a simpler way. Instead of manually handling the iterators, use:
for (auto a_students: s_stl_list)
{
// do something with each "a_students" which will be AUTOmatically the right type
}
I'm trying to check if the program stopped in a function in a TRACE32.
I know I can see the the functions in FRAME window but no idea how to copy them to a variable inside my script.
Any idea how to do that ?
You get the name of the function, where the program counter points to with:
PRINT sYmbol.FUNCTION(PP())
(Instead of printing the result you can also assign it to a macro.)
So one approach to check if you've stopped in function myFunc() would be:
PRINT STRing.ComPare(sYmbol.FUNCTION(PP()),"*\myFunc")
Another way is to check if the program counter is inside the first and last address of your function myFunc():
PRINT (ADDRESS.OFFSET(sYmbol.BEGIN(`myFunc`))<=Register(PP))&&(Register(PP)<=ADDRESS.OFFSET(sYmbol.END(`myFunc`)))
In one of my projects, I need to be able to provide a very simple variable find-and-replace parser (mostly for use in paths). Variables are used primarily during startup and occasionally to access files (not the program's primary function, just loading resources), so the parser need not be high-performance. I would greatly prefer it to be thread-safe, however.
The parser needs to be able to store a set of variables (map<string, string> at the moment) and be able to replace tokens with the corresponding value in strings. Variable values may contain other variables, which will be resolved when the variable is used (not when it is added, as variables may be added over time).
The current variable grammar looks something like:
$basepath$/resources/file.txt
/$drive$/$folder$/path/file
My current parser uses a pair of stringstreams ("output" and "varname"), writes to the "output" stream until it finds the first $, the "varname" stream until the second $, then looks up the variable (using the contents of varname.str()). It's very simple and works nicely, even when recursing over variable values.
String Parse(String input)
{
stringstream output, varname;
bool dest = false;
size_t total = input.length();
size_t pos = 0;
while ( pos < total )
{
char inchar = input[pos];
if ( inchar != '$' )
{
if ( dest ) output << inchar;
else varname << inchar;
} else {
// Is a varname start/end
if ( !dest )
{
varname.clear();
dest = true;
} else {
// Is an end
Variable = mVariables.find(varname.str());
output << Parse(Variable.value());
dest = false;
}
}
++pos;
}
return output.str();
}
(error checking and such removed)
However, that method fails me when I try to apply it to my desired grammar. I would like something similar to what Visual Studio uses for project variables:
$(basepath)/resources/file.txt
/$(drive)/$(folder)/path/file
I would also like to be able to do:
$(base$(path))/subdir/file
Recursing in the variable name has run me into a wall, and I'm not sure the best way to proceed.
I have, at the moment, two possible concepts:
Iterate over the input string until I find a $, look for a ( as the next character, then find the matching ) (counting levels in and out until the proper close paran is reached). Send that bit off to be parsed, then use the returned value as the variable name. This seems like it will be messy and cause a lot of copying, however.
The second concept is to use a char *, or perhaps char * &, and move that forward until I reach a terminating null. The parser function can use the pointer in recursive calls to itself while parsing variable names. I'm not sure how best to implement this technique, besides having each call keep track of the name it's parsed out, and append the returned value of any calls it makes.
The project need only compile in VS2010, so STL streams and strings, the supported bits of C++0x, and Microsoft-specific features are all fair game (a generic solution is preferable in case those reqs change, but it's not necessary at this point). Using other libraries is no good, though, especially not Boost.
Both my ideas seem like they're more complicated and messier than is needed, so I'm looking for a nice clean way of handling this. Code, ideas or documents discussing how best to do it are all very much welcome.
Simple solution is to search for the first ')' in the string, then move backwards to see if there's an identifier preceeded by "$(". If so, replace it and restart your scanning. If you don't find "$(" identifier, then find the next ')' - when there isn't one you're finished.
To explain: by searching for a ) you can be sure that you're finding a complete identifier for your substitution, which then has the chance to contribute to some other identifier used in a subsequent substitution.
EXAMPLE
Had a great time on $($(day)$(month)), did you?
Dictionary: "day" -> "1", "month" -> "April", "1April" -> "April Fools Day"
Had a great time on $($(day)$(month)), did you?
^ find this
Had a great time on $($(day)$(month)), did you?
^^^^^^ back up to match this complete substitution
Had a great time on $(1$(month)), did you?
^ substitution made, restart entire process...
Had a great time on $(1$(month)), did you?
^ find this
etc.
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.