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  • C: socket connection timeout

    - by The.Anti.9
    I have a simple program to check if a port is open, but I want to shorten the timeout length on the socket connection because the default is far too long. I'm not sure how to do this though. Here's the code: #include <sys/socket.h> #include <sys/time.h> #include <sys/types.h> #include <arpa/inet.h> #include <netinet/in.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <netdb.h> #include <stdlib.h> #include <string.h> #include <unistd.h> int main(int argc, char **argv) { u_short port; /* user specified port number */ char addr[1023]; /* will be a copy of the address entered by u */ struct sockaddr_in address; /* the libc network address data structure */ short int sock = -1; /* file descriptor for the network socket */ if (argc != 3) { fprintf(stderr, "Usage %s <port_num> <address>", argv[0]); return EXIT_FAILURE; } address.sin_addr.s_addr = inet_addr(argv[2]); /* assign the address */ address.sin_port = htons(atoi(argv[2])); /* translate int2port num */ sock = socket(AF_INET, SOCK_STREAM, 0); if (connect(sock,(struct sockaddr *)&address,sizeof(address)) == 0) { printf("%i is open\n", port); } close(sock); return 0; }

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  • tutorials/books to create a plugin/module/library?

    - by fayer
    i wonder if there are tutorials/books explaining how you create a library/plugin/module for other to implement? libraries/frameworks like solr, doctrine, codeigniter etc. cause it seems that they follow the same pattern. having one "bootstrap" file to load configurations, other classes and so on. i aim to understand the basics, so i can create a such library. cause at the moment i want to code an address book that other can use. just include a bootstrap file and they are ready to use my classes (like Doctrine). recommendations of sources to learn these things of stuff? you experienced guys, how did you learn it? thanks.

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  • running examples in package-Ex.R failed

    - by swarna
    Hi,My name is Swarna,I'm new to R,when i was checking my package i got a error message saying "Running examples in package-Ex.R failed" and series of statement saying where error might have occurred name of the package -package flush(stderr());flush(stdout()) name: title alias keywords Can any one please help me with this. Thank you,

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  • Need some testcases on solving this problem

    - by user285825
    I am trying to solve the minesweeper problem of acm problemset archive, http://uva,onlinejudge,org/index,php?option=com_onlinejudge&Itemid=8&category=13&page=show_problem&problem=1130 I tested with all the possible cases that I can imagine of: 1, minimum 1 1 , 1 1 # 2, maximum upto 100 upto 100 repeat until 100 3, for each position I test for mine 4 4 ,,, ,,,, ,,,, 4 4 ,#,, ,,,, ,,,, ,,,, lastly 4 4 ,,,, ,,,, ,,,, ,,,# 4, for each postion I put a ',' and surround it with mines 4 4 ,### # # # 4 4 , # # # lastly 4 4 # # # , I thought that these are reasonable and representative sets of testcases, But still Wrong answer, I am not sure what else could I test for, I would be glad if someone throw some light on further strategy to test this thing,

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  • Result of Long Positive Integers & Search and element in array..

    - by AGeek
    Hi, I have two Questions for which I cannot find answers by googling, but I find these questions very important for preparation.. Kindly explain only the logic, I will be able to code. In Search of Efficient Logic..... in terms of Memory and Time. WAP to add two long positive integers. What Data structure / data type we can use to store the numbers and result. What is the best way to search an element from an array in shortest time. Size of the array could be large enough, and any elements could be stored in the array(i.e. no range). Thanks.

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  • Passing a hostname of over 255 characters to getaddrinfo causes a getaddrinfo failed: memory allocat

    - by darrickc
    I am currently upgrading our software to support ipv6 and in the meantime I'm expanding hostname/ip fields to the max hostname size. In sun documentation it seems like this can be up to 1025 (netdb.h:#define NI_MAXHOST 1025 - this is the recommended hostname allocation define), but when I pass a hostname of over 255 to getaddrinfo I get "getaddrinfo failed: memory allocation failure". I am testing on a Sol10 box. Ideas?

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  • Daemonize() issues on Debian

    - by djTeller
    Hi, I'm currently writing a multi-process client and a multi-treaded server for some project i have. The server is a Daemon. In order to accomplish that, i'm using the following daemonize() code: static void daemonize(void) { pid_t pid, sid; /* already a daemon */ if ( getppid() == 1 ) return; /* Fork off the parent process */ pid = fork(); if (pid < 0) { exit(EXIT_FAILURE); } /* If we got a good PID, then we can exit the parent process. */ if (pid > 0) { exit(EXIT_SUCCESS); } /* At this point we are executing as the child process */ /* Change the file mode mask */ umask(0); /* Create a new SID for the child process */ sid = setsid(); if (sid < 0) { exit(EXIT_FAILURE); } /* Change the current working directory. This prevents the current directory from being locked; hence not being able to remove it. */ if ((chdir("/")) < 0) { exit(EXIT_FAILURE); } /* Redirect standard files to /dev/null */ freopen( "/dev/null", "r", stdin); freopen( "/dev/null", "w", stdout); freopen( "/dev/null", "w", stderr); } int main( int argc, char *argv[] ) { daemonize(); /* Now we are a daemon -- do the work for which we were paid */ return 0; } I have a strange side effect when testing the server on Debian (Ubuntu). The accept() function always fail to accept connections, the pid returned is -1 I have no idea what causing this, since in RedHat & CentOS it works well. When i remove the call to daemonize(), everything works well on Debian, when i add it back, same accept() error reproduce. I've been monitring the /proc//fd, everything looks good. Something in the daemonize() and the Debian release just doesn't seem to work. (Debian GNU/Linux 5.0, Linux 2.6.26-2-286 #1 SMP) Any idea what causing this? Thank you

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  • Stop NSXMLParser Instance from Causing _NSAutoreleaseNoPool

    - by PF1
    Hi Everyone: In my iPhone application, I have an instance of NSXMLParser that is set to a custom delegate to read the XML. This is then moved into its own thread so it can update the data in the background. However, ever since I have done this, it has been giving me a lot of _NSAutoreleaseNoPool warnings in the console. I have tried to add a NSAutoreleasePool to each of my delegate classes, however, this hasn't seemed to solve the problem. I have included my method of creating the NSXMLParser in case that is at fault. NSURL *url = [[NSURL alloc] initWithString:@"http://www.mywebsite.com/xmlsource.xml"]; NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:url]; CustomXMLParser *parser = [[CustomXMLParser alloc] init]; parser.managedObjectContext = self.managedObjectContext; parser = [parser initXMLParser]; [xmlParser setDelegate:parser]; [NSThread detachNewThreadSelector:@selector(parse) toTarget:xmlParser withObject:nil]; If anyone has any ideas to get rid of this problem, I would really appreciate it. Thanks.

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  • How to cast a character to int in Clojure?

    - by Learning Clojure
    How to cast a character to int in Clojure? I am trying to write a rot 13 in clojure, so I need to have something to cast my char to int. I found something called (int), so I put: (int a) Get: CompilerException java.lang.RuntimeException: Unable to resolve symbol: a in this context, compiling:(NO_SOURCE_PATH:13:1) Then I put: (int 'a) Get: ClassCastException clojure.lang.Symbol cannot be cast to java.lang.Character clojure.lang.RT.intCast (RT.java:1087) Then: (rot13 ''a') Get: ClassCastException clojure.lang.PersistentList cannot be cast to java.lang.Character clojure.lang.RT.intCast (RT.java:1087) And: (rot13 "a") Get: ClassCastException java.lang.String cannot be cast to java.lang.Character clojure.lang.RT.intCast (RT.java:1087) So what is the right way to do it? btw, I always get confused with all these clojure syntax. But I can never find any source only help me with my problem. Any suggestions? Thank you!!

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  • Most efficient way for testing links

    - by Burnzy
    I'm currently developping an app that is going through all the files on a server and checking every single hrefs to check wether they are valid or not. Using a WebClient or a HttpWebRequest/HttpWebResponse is kinda overkilling the process because it downloads the whole page each time, which is useless, I only need to check if the link do not return 404. What would be the most efficient way? Socket seems to be a good way of doing it, however I'm not quite sure how this works. Thanks for sharing your expertise!

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  • which ad solution is best for iPhone apps

    - by nbojja
    Hi All, i have a iPhone free app downloaded by 3000 users. mostly every one uses my app atleast once in a day. So i am planning to keep ads on my app. Which ad solution is best. and i looked in some sites. No one is giving clear details about CPMs. my direct question is "How much will i get for 1000 impressions using different ad solutions?" thanks

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  • recvfrom returns invalid argument when *from* is passed

    - by Aditya Sehgal
    I am currently writing a small UDP server program in linux. The UDP server will receive packets from two different peers and will perform different operations based on from which peer it received the packet. I am trying to determine the source from where I receive the packet. However, when select returns and recvfrom is called, it returns with an error of Invalid Argument. If I pass NULL as the second last arguments, recvfrom succeeds. I have tried declaring fromAddr as struct sockaddr_storage, struct sockaddr_in, struct sockaddr without any success. Is their something wrong with this code? Is this the correct way to determine the source of the packet? The code snippet follows. ` /*TODO : update for TCP. use recv */ if((pkInfo->rcvLen=recvfrom(psInfo->sockFd, pkInfo->buffer, MAX_PKTSZ, 0, /* (struct sockaddr*)&fromAddr,*/ NULL, &(addrLen) )) < 0) { perror("RecvFrom failed\n"); } else { /*Apply Filter */ #if 0 struct sockaddr_in* tmpAddr; tmpAddr = (struct sockaddr_in* )&fromAddr; printf("Received Msg From %s\n",inet_ntoa(tmpAddr->sin_addr)); #endif printf("Packet Received of len = %d\n",pkInfo->rcvLen); } `

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  • simple question on C

    - by lego69
    I have this snippet of the code char *str = “123”; if(str[0] == 1) printf("Hello\n"); why I can't receive my Hello thanks in advance! how exactly compiler does this comparison if(str[0] == 1)?

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  • What happens when we say "listen to a port" ?

    - by smwikipedia
    Hi, When we start a server application, we always need to speicify the port number it listens to. But how is this "listening mechanism" implemented under the hood? My current imagination is like this: The operating system associate the port number with some buffer. The server application's responsibiligy is to monitor this buffer. If there's no data in this buffer, the server application's listen operation will just block the application. When some data arrives from the wire, the operating system will know that check the data and see if it is targed at this port number. And then it will fill the buffer. And then OS will notify the blocked server application and the server application will get the data and continue to run. Question is: If the above scenario is correct, how could the opearting system know there's data arriving from wire? It cannot be a busy pooling. Is it some kind of interrupt-based mechanism? If there's too much data arriving and the buffer is not big enough, will there be data loss? Is the "listen to a port" operation really a blocking operation? Many thanks.

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  • How do I use Declarations (type, inline, optimize) in Scheme?

    - by kunjaan
    How do I declare the types of the parameters in order to circumvent type checking? How do I optimize the speed to tell the compiler to run the function as fast as possible like (optimize speed (safety 0))? How do I make an inline function in Scheme? How do I use an unboxed representation of a data object? And finally are any of these important or necessary? Can I depend on my compiler to make these optimizations? thanks, kunjaan.

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  • heeeeeeeeeeeeeeelp

    - by Yassin
    plz help me i need to make asimple calculator using c for example (1+2-44)/7 but it requiers reverse polish notation which i cant under stand if any one could help me giving me the code i'll be greatfull cause i have an exam after 2 days

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