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  • DELETE and EDIT is not working in my python program

    - by user2968025
    This is a simple python program that ADD, DELETE, EDIT and VIEW student records. The problem is, DELETE and EDIT is not working. I dont know why but when I tried removing one '?' in the DELETE dunction, I had the error that says there are only 8 columns and it needs 10. But originally, there are only 9 columns. I don't know where it got the other one to make it 10. Please help.. :( import sys import sqlite3 import tkinter import tkinter as tk from tkinter import * from tkinter.ttk import * def newRecord(): studentnum="" name="" age="" birthday="" address="" email="" course="" year="" section="" con=sqlite3.connect("Students.db") cur=con.cursor() cur.execute("CREATE TABLE IF NOT EXISTS student(studentnum TEXT, name TEXT, age TEXT, birthday TEXT, address TEXT, email TEXT, course TEXT, year TEXT, section TEXT)") def save(): studentnum=en1.get() name=en2.get() age=en3.get() birthday=en4.get() address=en5.get() email=en6.get() course=en7.get() year=en8.get() section=en9.get() student=(studentnum,name,age,birthday,address,email,course,year,section) cur.execute("INSERT INTO student(studentnum,name,age,birthday,address,email,course,year,section) VALUES(?,?,?,?,?,?,?,?,?)",student) con.commit() win=tkinter.Tk();win.title("Students") lbl=tkinter.Label(win,background="#000",foreground="#ddd",width=30,text="Add Record") lbl.pack() lbl1=tkinter.Label(win,width=30,text="Student Number : ") lbl1.pack() en1=tkinter.Entry(win,width=30) en1.pack() lbl2=tkinter.Label(win,width=30,text="Name : ") lbl2.pack() en2=tkinter.Entry(win,width=30) en2.pack() lbl3=tkinter.Label(win,width=30,text="Age : ") lbl3.pack() en3=tkinter.Entry(win,width=30) en3.pack() lbl4=tkinter.Label(win,width=30,text="Birthday : ") lbl4.pack() en4=tkinter.Entry(win,width=30) en4.pack() lbl5=tkinter.Label(win,width=30,text="Address : ") lbl5.pack() en5=tkinter.Entry(win,width=30) en5.pack() lbl6=tkinter.Label(win,width=30,text="Email : ") lbl6.pack() en6=tkinter.Entry(win,width=30) en6.pack() lbl7=tkinter.Label(win,width=30,text="Course : ") lbl7.pack() en7=tkinter.Entry(win,width=30) en7.pack() lbl8=tkinter.Label(win,width=30,text="Year : ") lbl8.pack() en8=tkinter.Entry(win,width=30) en8.pack() lbl9=tkinter.Label(win,width=30,text="Section : ") lbl9.pack() en9=tkinter.Entry(win,width=30) en9.pack() btn1=tkinter.Button(win,background="#000",foreground="#ddd",width=30,text="Save Student",command=save) btn1.pack() def editRecord(): studentnum1="" def edit(): studentnum1=en10.get() studentnum="" name="" age="" birthday="" address="" email="" course="" year="" section="" con=sqlite3.connect("Students.db") cur=con.cursor() row=cur.fetchone() cur.execute("DELETE FROM student WHERE name = '%s'" % studentnum1) con.commit() def save(): studentnum=en1.get() name=en2.get() age=en3.get() birthday=en4.get() address=en5.get() email=en6.get() course=en7.get() year=en8.get() section=en8.get() student=(studentnum,name,age,email,birthday,address,email,course,year,section) cur.execute("INSERT INTO student(studentnum,name,age,email,birthday,address,email,course,year,section) VALUES(?,?,?,?,?,?,?,?,?)",student) con.commit() win=tkinter.Tk();win.title("Students") lbl=tkinter.Label(win,background="#000",foreground="#ddd",width=30,text="Edit Reocrd :"+'\t'+studentnum1) lbl.pack() lbl1=tkinter.Label(win,width=30,text="Student Number : ") lbl1.pack() en1=tkinter.Entry(win,width=30) en1.pack() lbl2=tkinter.Label(win,width=30,text="Name : ") lbl2.pack() en2=tkinter.Entry(win,width=30) en2.pack() lbl3=tkinter.Label(win,width=30,text="Age : ") lbl3.pack() en3=tkinter.Entry(win,width=30) en3.pack() lbl4=tkinter.Label(win,width=30,text="Birthday : ") lbl4.pack() en4=tkinter.Entry(win,width=30) en4.pack() lbl5=tkinter.Label(win,width=30,text="Address : ") lbl5.pack() en5=tkinter.Entry(win,width=30) en5.pack() lbl6=tkinter.Label(win,width=30,text="Email : ") lbl6.pack() en6=tkinter.Entry(win,width=30) en6.pack() lbl7=tkinter.Label(win,width=30,text="Course : ") lbl7.pack() en7=tkinter.Entry(win,width=30) en7.pack() lbl8=tkinter.Label(win,width=30,text="Year : ") lbl8.pack() en8=tkinter.Entry(win,width=30) en8.pack() lbl9=tkinter.Label(win,width=30,text="Section : ") lbl9.pack() en9=tkinter.Entry(win,width=30) en9.pack() btn1=tkinter.Button(win,background="#000",foreground="#ddd",width=30,text="Save Record",command=save) btn1.pack() win=tkinter.Tk();win.title("Edit Student") lbl=tkinter.Label(win,background="#000",foreground="#ddd",width=30,text="Edit Record") lbl.pack() lbl10=tkinter.Label(win,width=30,text="Student Number : ") lbl10.pack() en10=tkinter.Entry(win) en10.pack() btn2=tkinter.Button(win,background="#000",foreground="#ddd",width=30,text="Edit",command=edit) btn2.pack() def deleteRecord(): studentnum1="" win=tkinter.Tk();win.title("Delete Student Record") lbl=tkinter.Label(win,background="#000",foreground="#ddd",width=30,text="Delete Record") lbl.pack() lbl10=tkinter.Label(win,text="Student Number") lbl10.pack() en10=tkinter.Entry(win) en10.pack() def delete(): studentnum1=en10.get() con=sqlite3.connect("Students.db") cur=con.cursor() row=cur.fetchone() cur.execute("DELETE FROM student WHERE name = '%s';" % studentnum1) con.commit() win=tkinter.Tk();win.title("Record Deleted") lbl=tkinter.Label(win,background="#000",foreground="#ddd",width=30,text="Record Deleted :") lbl.pack() lbl=tkinter.Label(win,width=30,text=studentnum1) lbl.pack() btn=tkinter.Button(win,background="#000",foreground="#ddd",width=30,text="Ok",command=win.destroy) btn.pack() btn2=tkinter.Button(win,background="#000",foreground="#ddd",width=30,text="Delete",command=delete) btn2.pack() def viewRecord(): con=sqlite3.connect("Students.db") cur=con.cursor() win=tkinter.Tk();win.title("View Student Record"); row=cur.fetchall() lbl1=tkinter.Label(win,background="#000",foreground="#ddd",width=300,text="\n\tStudent Number"+"\t\tName"+"\t\tAge"+"\t\tBirthday"+"\t\tAddress"+"\t\tEmail"+"\t\tCourse"+"\t\tYear"+"\t\nSection") lbl1.pack() for row in cur.execute("SELECT * FROM student"): lbl2=tkinter.Label(win,width=300,text= row[0] + '\t\t' + row[1] + '\t' + row[2] + '\t\t' + row[3] + '\t\t' + row[4] + '\t\t' + row[5] + '\t\t' + row[6] + '\t\t' + row[7] + '\t\t' + row[8] + '\n') lbl2.pack() con.close() but1=tkinter.Button(win,background="#000",foreground="#fff", width=150,text="Close",command=win.destroy) but1.pack() root=tkinter.Tk();root.title("Student Records") menubar=tkinter.Menu(root) manage=tkinter.Menu(menubar,tearoff=0) manage.add_command(label='New Record',command=newRecord) manage.add_command(label='Edit Record',command=editRecord) manage.add_command(label='Delete Record',command=deleteRecord) menubar.add_cascade(label='Manage',menu=manage) view=tkinter.Menu(menubar,tearoff=0) view.add_command(label='View Record',command=viewRecord) menubar.add_cascade(label='View',menu=view) root.config(menu=menubar) lbl=tkinter.Label(root,background="#000",foreground="#ddd",font=("Verdana",15),width=30,text="Student Records") lbl.pack() lbl1=tkinter.Label(root,text="\nSubmitted by :") lbl1.pack() lbl2=tkinter.Label(root,text="Chavez, Vissia Nicole P") lbl2.pack() lbl3=tkinter.Label(root,text="BSIT 4-4") lbl3.pack()

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  • Time complexity of Sieve of Eratosthenes algorithm

    - by eSKay
    From Wikipedia: The complexity of the algorithm is O(n(logn)(loglogn)) bit operations. How do you arrive at that? That the complexity includes the loglogn term tells me that there is a sqrt(n) somewhere. Suppose I am running the sieve on the first 100 numbers (n = 100), assuming that marking the numbers as composite takes constant time (array implementation), the number of times we use mark_composite() would be something like n/2 + n/3 + n/5 + n/7 + ... + n/97 = O(n) And to find the next prime number (for example to jump to 7 after crossing out all the numbers that are multiples of 5), the number of operations would be O(n). So, the complexity would be O(n^2). Do you agree?

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  • STFT and ISTFT in Python

    - by endolith
    Is there any form of short-time Fourier transform with corresponding inverse transform built into SciPy or NumPy or whatever? There's the pyplot specgram function in matplotlib, which calls ax.specgram(), which calls mlab.specgram(), which calls _spectral_helper(): #The checks for if y is x are so that we can use the same function to #implement the core of psd(), csd(), and spectrogram() without doing #extra calculations. We return the unaveraged Pxy, freqs, and t. I'm not sure if this can be used to do an STFT and ISTFT, though. Is there anything else, or should I translate something like this?

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  • Compile-time lookup array creation for ANSI-C?

    - by multiproximus
    A previous programmer preferred to generate large lookup tables (arrays of constants) to save runtime CPU cycles rather than calculating values on the fly. He did this by creating custom Visual C++ projects that were unique for each individual lookup table... which generate array files that are then #included into a completely separate ANSI-C micro-controller (Renesas) project. This approach is fine for his original calculation assumptions, but has become tedious when the input parameters need to be modified, requiring me to recompile all of the Visual C++ projects and re-import those files into the ANSI-C project. What I would like to do is port the Visual C++ source directly into the ANSI-C microcontroller project and let the compiler create the array tables. So, my question is: Can ANSI-C compilers compute and generate lookup arrays during compile time? And if so, how should I go about it? Thanks in advance for your help!

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  • JFormattedTextField : input time duration value

    - by bguiz
    I want to use a JFormattedTextField to allow the user to input time duration values into a form. Sample valid values are: 2h 30m 72h 15m 6h 0h However I am having limited success with this. Can some one please suggest how this can be accomplished? I am OK if this result can be achieved using a JTextField as well. Thanks! If it is worth anything, here's my current attempt: mFormattedText.setFormatterFactory( new DefaultFormatterFactory( new DateFormatter( new SimpleDateFormat("H mm")))); This sorta works except that: I cannot get h and m to appear as plain text (I tried escaping) * The number of hours has a max *: See @nanda's answer

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  • Python: slicing a very large binary file

    - by Duncan Tait
    Say I have a binary file of 12GB and I want to slice 8GB out of the middle of it. I know the position indices I want to cut between. How do I do this? Obviously 12GB won't fit into memory, that's fine, but 8GB won't either... Which I thought was fine, but it appears binary doesn't seem to like it if you do it in chunks! I was appending 10MB at a time to a new binary file and there are discontinuities on the edges of each 10MB chunk in the new file. Is there a Pythonic way of doing this easily?

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  • Common Pitfalls in Python

    - by Anurag Uniyal
    Today I was bitten again by "Mutable default arguments" after many years. I usually don't use mutable default arguments unless needed but I think with time I forgot about that, and today in the application I added tocElements=[] in a pdf generation function's argument list and now 'Table of Content' gets longer and longer after each invocation of "generate pdf" :) My question is what other things should I add to my list of things to MUST avoid? Mutable default arguments Import modules always same way e.g. from y import x and import x are different things, they are treated as different modules. Do not use range in place of lists because range() will become an iterator anyway, the following will fail: myIndexList = [0,1,3] isListSorted = myIndexList == range(3) # will fail in 3.0 isListSorted = myIndexList == list(range(3)) # will not same thing can be mistakenly done with xrange: `myIndexList == xrange(3)`. Catching multiple exceptions try: raise KeyError("hmm bug") except KeyError,TypeError: print TypeError It prints "hmm bug", though it is not a bug, it looks like we are catching exceptions of type KeyError,TypeError but instead we are catching KeyError only as variable TypeError, use this instead: try: raise KeyError("hmm bug") except (KeyError,TypeError): print TypeError

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  • Python - urllib2 & cookielib

    - by Adrian
    I am trying to open the following website and retrieve the initial cookie and use it for the second url-open BUT if you run the following code it outputs 2 different cookies. How do I use the initial cookie for the second url-open? import cookielib, urllib2 cj = cookielib.CookieJar() opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj)) home = opener.open('https://www.idcourts.us/repository/start.do') print cj search = opener.open('https://www.idcourts.us/repository/partySearch.do') print cj Output shows 2 different cookies every time as you can see: <cookielib.CookieJar[<Cookie JSESSIONID=0DEEE8331DE7D0DFDC22E860E065085F for www.idcourts.us/repository>]> <cookielib.CookieJar[<Cookie JSESSIONID=E01C2BE8323632A32DA467F8A9B22A51 for www.idcourts.us/repository>]>

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  • python urllib2 thread safety

    - by jldupont
    Is urllib2 thread safe? I find that using urllib2.urlopen sometimes results in the thread issuing the call to stop functioning. Yes I have used the timeout option to no avail. Is there a thread safe HTTP GET functionality I could use? NOTE: I am not interested in using Twisted to solve this problem. I have used Twisted in the past and I love it but this time I need a simpler solution. NOTE2: I also tried httplib with the same result (blocking).

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  • Table alias has an effect with execution time?

    - by RedFux227
    So I have this query : SELECT A.e_cd "INFLATE" , A.ccgpt "1" , ( SELECT J.comp FROM JBB J WHERE J.e_cd=A.e_cd AND emplo_RCD=:1 AND J.Dte = ( SELECT MAX(J1.Dte) FROM JBB J1 WHERE J.e_cd=J1.e_cd AND TO_CHAR(J1.Dte,'MM') <=A.mth_to AND TO_CHAR(J1.Dte,'YYYY') <=A.year ) AND J.seq = ( SELECT MAX(J2.seq) FROM PS_JOB J2 WHERE J2.e_cd=J.e_cd AND J2.Dte=J.Dte)) "Company" FROM PPS A WHERE orcd=:2 AND rcd=:3 AND tx_cd=:4 AND year=:5 With this one : SELECT A.e_cd "INFLATE" , A.ccgpt "1" , ( SELECT J.comp FROM JBB J WHERE J.e_cd=A.e_cd AND emplo_RCD=:1 AND J.Dte = ( SELECT MAX(J1.Dte) FROM JBB J1 WHERE J.e_cd=J1.e_cd AND TO_CHAR(J1.Dte,'MM') <=A.mth_to AND TO_CHAR(J1.Dte,'YYYY') <=A.year ) AND J.seq = ( SELECT MAX(J1.seq) **FROM PS_JOB J1 WHERE J1.e_cd=J.e_cd AND J1.Dte=J.Dte**)) "Company" FROM PPS A WHERE orcd=:2 AND rcd=:3 AND tx_cd=:4 AND year=:5 The 1st query run for about 3.20 sec with buffer gets 8,134 and for the 2nd query it run for about 1.73 sec with buffer gets 7,006. So, is the table alias somehow has an impact on the execution time / buffer gets? Thanks in advance!

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  • Adding time zone hours difference to time

    - by Hwang
    I know there's a much better and correct way to do it, but i need a temporarily solutions. I need to add in extra hours to the time, and the day will change automatically too. How should I change the code below? package { public class getTime { private var today:Date=new Date(); private var hour:uint=today.getHours(); private var minute:uint=today.getMinutes(); private var month:uint=today.getMonth(); private var monthArray:Array=new Array('January','February','March','April','May','June','July','August','September','October','November','December'); private var time:String = getUSClockTime(today.getHours(), today.getMinutes()); public var dateNtime:String=(time+", " +today.getDate()+" "+monthArray[month]+" "+today.getFullYear());; public function getTime() { } private function getUSClockTime(hrs:uint, mins:uint):String { var modifier:String="PM"; var minLabel:String=doubleDigitFormat(mins); if (hrs>12) { hrs=hrs-12; } else if (hrs == 0) { modifier="AM"; hrs=12; } else if (hrs < 12) { modifier="AM"; } return (doubleDigitFormat(hrs) + ":" + minLabel + " " + modifier); } private function doubleDigitFormat(num):String { if (num<10) { return ("0" + num); } return num; } } }

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  • How should I use random.jumpahead in Python

    - by Peter Smit
    I have a application that does a certain experiment 1000 times (multi-threaded, so that multiple experiments are done at the same time). Every experiment needs appr. 50.000 random.random() calls. What is the best approach to get this really random. I could copy a random object to every experiment and do than a jumpahead of 50.000 * expid. The documentation suggests that jumpahead(1) already scrambles the state, but is that really true? Or is there another way to do this in 'the best way'? (No, the random numbers are not used for security, but for a metropolis hasting algorithm. The only requirement is that the experiments are independent, not whether the random sequence is somehow predictable or so)

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  • Python - Number of Significant Digits in results of division

    - by russ
    Newbie here. I have the following code: myADC = 128 maxVoltage = 5.0 maxADC = 255.0 VoltsPerADC = maxVoltage/maxADC myVolts = myADC * VoltsPerADC print "myADC = {0: >3}".format(myADC) print "VoltsPerADC = {0: >7}".format(VoltsPerADC) print VoltsPerADC print "myVolts = {0: >7}".format(myVolts) print myVolts This outputs the following: myADC = 128 VoltsPerADC = 0.0196078 0.0196078431373 myVolts = 2.5098 2.50980392157 I have been searching for an explanation of how the number of significant digits is determined by default, but have had trouble locating an explanation that makes sense to me. This link link text suggests that by default the "print" statement prints numbers to 10 significant figures, but that does not seem to be the case in my results. How are the number of significant digits/precision determined? Can someone shed some light on this for me. Thanks in advance for your time and patience.

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  • Python Threading

    - by anteater7171
    I'm trying to make a simple program that continually displays and updates a label that displays the CPU usage, while having other unrelated things going on. I've done enough research to know that threading is likely going to be involved. However, I'm having trouble applying what I've seen in simple examples of threading to what I'm trying to do. What I currently have going: import Tkinter import psutil,time from PIL import Image, ImageTk class simpleapp_tk(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): self.labelVariable = Tkinter.StringVar() self.label = Tkinter.Label(self,textvariable=self.labelVariable) self.label.pack() self.button = Tkinter.Button(self,text='button',command=self.A) self.button.pack() def A (self): G = str(round(psutil.cpu_percent(), 1)) + '%' print G self.labelVariable.set(G) def B (self): print "hello" if __name__ == "__main__": app = simpleapp_tk(None) app.mainloop() In the above code I'm basically trying to get command A continually running, while allowing command B to be done when the users presses the button.

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  • Rails 3 time output

    - by Oluf Nielsen
    Hi, I'm now working on my output of the feeds I'm taking in from some site. What I'm currently doing is Time, and i want it to be displayed in a maybe, little be special way.. like this.. today, 14:12 yesterday, 15:34 27/12, 15:24 i have this in my code = news.entry_published.strftime("%d/%m, %H:%M") That gives me an error saying undefined method `strftime' for "2010-12-30 19:26:00.000000":String And it dosn't do what i want with the days.. Edit: - @date = DateTime.strptime(news.entry_published, "%Y-%m-%d %H:%M:%S") = @date.strftime("%d/%m, %H:%M") Now works, and gives this output 30/12, 19:26 But i still have to check if it is today, yesterday or just another day. Cheers, Oluf.

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  • How to get progress bar to time Class exectution

    - by chrissygormley
    Hello, I am trying to use progress bar to show the progress of a script. I want it increase progress after every function in a class is executed. The code I have tried is below: import progressbar from time import sleep class hello(): def no(self): print 'hello!' def yes(self): print 'No!!!!!!' def pro(): bar = progressbar.ProgressBar(widgets=[progressbar.Bar('=', '[', ']'), ' ', progressbar.Percentage()]) for i in Yep(): bar.update(Yep.i()) sleep(0.1) bar.finish() if __name__ == "__main__": Yep = hello() pro() Does anyone know how to get this working. Thanks

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  • Adding controls dynamically at design time vb.net

    - by chris
    I have been developing some custom smart tags. I am using a DesignerActionMethodItem which gets me to a fired method in code. When I try to hit the controls.Add the control is added but it seems the designer is unaware of it. It is never serialized and it goes away when the form is refreshed in the designer. Any help would be greatly appreciated. I am sort of stuck and google hasn't helped me. Please don't send me anything about smart tags that has nothing to do with adding controls dynamically at design time, I have already read so many looking for this.

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  • Huge amount of time sending data with suds and proxy

    - by Roman
    Hi everyone, I have the following code to send data through a proxy using suds: import suds t = suds.transport.http.HttpTransport() proxy = urllib2.ProxyHandler({'http': 'http://192.168.3.217:3128'}) opener = urllib2.build_opener(proxy) t.urlopener = opener ws = suds.client.Client('http://xxxxxxx/web.asmx?WSDL', transport=t) req = ws.factory.create('ActionRequest.request') req.SerialNumber = 'asdf' req.HostName = 'hola' res = ws.service.ActionRequest(req) I don't know why, but it can be sending data above 2 or 3 minutes, or even more and it raises a "Gateway timeout" exception sometimes. If I don't use the proxy, the amount of time used is above 2 seconds or less. Here is the SOAP reply: (ActionResponse){ Id = None Action = "Action.None" Objects = "" } The proxy is running right with other requests through urllib2, or using normal web browsers like firefox. Does anyone have any idea what's happening here with suds? Thanks a lot in advance!!!

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  • Reducing load time, or making the user think the load time is less

    - by Malfist
    I've been working on a website, and we've managed to reduce the total content for a page load from 13.7MiB's to 2.4, but the page still takes forever to load. It's a joomla site (ick), and it has a lot of redundant DOM elements (2000+ for the home page), and make 60+ HttpRequest's per page load, counting all the css, js, and image requests. Unlike drupal, joomla won't merge them all on the fly, and they have to be kept separate or else the joomla components will go nuts. What can I do to improve load time? Things I've done: Added colors to dom elements that have large images as their background so the color is loaded, then the image Reduced excessively large images to much smaller file sizes Reduced DOM elements to ~2000, from ~5000 Loading CSS at the start of the page, and javascript at the end Not totally possible, joomla injects it's own javascript and css and it does it at the header, always. Minified most javascript Setup caching and gziping on server Uncached size 2.4MB, cached is ~300KB, but even with so many dom elements, the page takes a good bit of time to render. What more can I do to improve the load time?

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  • Key word extraction in Python

    - by oliland
    I'm building a website in django that needs to extract key words from short (twitter-like) messages. I've looked at packages like topia.textextract and nltk - but both seem to be overkill for what I need to do. All I need to do is filter words like "and", "or", "not" while keeping nouns and verbs that aren't conjunctives or other parts of speech. Are there any "simpler" packages out there that can do this? EDIT: This needs to be done in near real-time on a production website, so using a keyword extraction service seems out of the question, based on their response times and request throttling.

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  • sorting content of a text file in python

    - by rabidmachine9
    I have this small script that sorts the content of a text file # The built-in function `open` opens a file and returns a file object. # Read mode opens a file for reading only. try: f = open("tracks.txt", "r") try: # Read the entire contents of a file at once. # string = f.read() # OR read one line at a time. #line = f.readline() # OR read all the lines into a list. lines = f.readlines() lines.sort() f = open('tracks.txt', 'w') f.writelines(lines) # Write a sequence of strings to a file finally: f.close() except IOError: pass the only problem is that the text is displayed at the bottom of the text file everytime it's sortened... I assume it also sorts the blank lines...anybody knows why? thanks in advance

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  • compile time if && return string reference optimization

    - by Truncheon
    Hi. I'm writing a series classes that inherit from a base class using virtual. They are INT, FLOAT and STRING objects that I want to use in a scripting language. I'm trying to implement weak typing, but I don't want STRING objects to return copies of themselves when used in the following way (instead I would prefer to have a reference returned which can be used in copying): a = "hello "; b = "world"; c = a + b; I have written the following code as a mock example: #include <iostream> #include <string> #include <cstdio> #include <cstdlib> std::string dummy("<int object cannot return string reference>"); struct BaseImpl { virtual bool is_string() = 0; virtual int get_int() = 0; virtual std::string get_string_copy() = 0; virtual std::string const& get_string_ref() = 0; }; struct INT : BaseImpl { int value; INT(int i = 0) : value(i) { std::cout << "constructor called\n"; } INT(BaseImpl& that) : value(that.get_int()) { std::cout << "copy constructor called\n"; } bool is_string() { return false; } int get_int() { return value; } std::string get_string_copy() { char buf[33]; sprintf(buf, "%i", value); return buf; } std::string const& get_string_ref() { return dummy; } }; struct STRING : BaseImpl { std::string value; STRING(std::string s = "") : value(s) { std::cout << "constructor called\n"; } STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } bool is_string() { return true; } int get_int() { return atoi(value.c_str()); } std::string get_string_copy() { return value; } std::string const& get_string_ref() { return value; } }; struct Base { BaseImpl* impl; Base(BaseImpl* p = 0) : impl(p) {} ~Base() { delete impl; } }; int main() { Base b1(new INT(1)); Base b2(new STRING("Hello world")); Base b3(new INT(*b1.impl)); Base b4(new STRING(*b2.impl)); std::cout << "\n"; std::cout << b1.impl->get_int() << "\n"; std::cout << b2.impl->get_int() << "\n"; std::cout << b3.impl->get_int() << "\n"; std::cout << b4.impl->get_int() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_ref() << "\n"; std::cout << b2.impl->get_string_ref() << "\n"; std::cout << b3.impl->get_string_ref() << "\n"; std::cout << b4.impl->get_string_ref() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_copy() << "\n"; std::cout << b2.impl->get_string_copy() << "\n"; std::cout << b3.impl->get_string_copy() << "\n"; std::cout << b4.impl->get_string_copy() << "\n"; return 0; } It was necessary to add an if check in the STRING class to determine whether its safe to request a reference instead of a copy: Script code: a = "test"; b = a; c = 1; d = "" + c; /* not safe to request reference by standard */ C++ code: STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } If was hoping there's a way of moving that if check into compile time, rather than run time.

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  • Working with multiple input and output files in Python

    - by Morlock
    I need to open multiple files (2 input and 2 output files), do complex manipulations on the lines from input files and then append results at the end of 2 output files. I am currently using the following approach: in_1 = open(input_1) in_2 = open(input_2) out_1 = open(output_1, "w") out_2 = open(output_2, "w") # Read one line from each 'in_' file # Do many operations on the DNA sequences included in the input files # Append one line to each 'out_' file in_1.close() in_2.close() out_1.close() out_2.close() The files are huge (each potentially approaching 1Go, that is why I am reading through these input files one at a time. I am guessing that this is not a very Pythonic way to do things. :) Would using the following form good? with open("file1") as f1: with open("file2") as f2: # etc. If yes, could I do it while avoiding the highly indented code that would result? Thanks for the insights!

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  • Django/Python: Save an HTML table to Excel

    - by kchau
    I have an HTML table that I'd like to be able to export to an Excel file. I already have an option to export the table into an IQY file, but I'd prefer something that didn't allow the user to refresh the data via Excel. I just want a feature that takes a snapshot of the table at the time the user clicks the link/button. I'd prefer it if the feature was a link/button on the HTML page that allows the user to save the query results displayed in the table. Is there a way to do this at all? Or, something I can modify with the IQY? I can try to provide more details if needed. Thanks in advance.

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  • crashing out in a while loop python

    - by Edward
    How to solve this error? i want to pass the values from get_robotxya() and get_ballxya() and use it in a loop but it seems that it will crash after awhile how do i fix this? i want to get the values whithout it crashing out of the while loop import socket import os,sys import time from threading import Thread HOST = '59.191.193.59' PORT = 5555 COORDINATES = [] def connect(): globals()['client_socket'] = socket.socket(socket.AF_INET, socket.SOCK_STREAM) client_socket.connect((HOST,PORT)) def update_coordinates(): connect() screen_width = 0 screen_height = 0 while True: try: client_socket.send("loc\n") data = client_socket.recv(8192) except: connect(); continue; globals()['COORDINATES'] = data.split() if(not(COORDINATES[-1] == "eom" and COORDINATES[0] == "start")): continue if (screen_width != int(COORDINATES[2])): screen_width = int(COORDINATES[2]) screen_height = int(COORDINATES[3]) return def get_ballxy(): update_coordinates() ballx = int(COORDINATES[8]) bally = int(COORDINATES[9]) return ballx,bally def get_robotxya(): update_coordinates() robotx = int(COORDINATES[12]) roboty = int(COORDINATES[13]) angle = int(COORDINATES[14]) return robotx,roboty,angle def print_ballxy(bx,by): print bx print by def print_robotxya(rx,ry,a): print rx print ry print a def activate(): bx,by = get_ballxy() rx,ry,a = get_robotxya() print_ballxy(bx,by) print_robotxya(rx,ry,a) Thread(target=update_coordinates).start() while True: activate() this is the error i get:

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