Writing C DLLs for use with VB Author: David Zimmer Site: Environment: VB6 + VC6 As your VB coding develops, one of the logical steps is to learn how to integrate in C/C++ code with your VB projects. There are allot of reasons you might want to do this. This article is an introduction to writing C Dlls for use with VB. This article is half discussion, half tips and tricks. If you are new to C and maybe even writing API declarations...it will take time to soak it all up, and you will have to search out other resources to help drive in the ideas. I personally recommend all of the books above, and I consider them professional level references that are worthy of any professional developers library. The example project download will show you several ways to pass strings to your C DLL, how to use Variants, SafeArrays, standard arrays use call back functions, and even inline asm. First let me introduce you to some Visual C terminology. Lets see an example. Now onto our
How to Pick a Language How do you pick a programming language, to learn or to use for a project? This article probably overlaps a lot with what others have already said on this topic . But I try to add a categorization of programming languages that reflects the way they are discussed on blogs and discussion sites. I think these categories are often implicit in discussions on the programming sub-reddit, Hacker News, or Lambda the Ultimate, but never made explicit for the benefit of younger developers. Each section describes languages in a category, how they are similar, and what distinguishes them from each other, along with a little history. Let me know if these categories make sense to you, or what you think a better categorization might be. 1. C appears often on lists of languages every programmer should know. A common answer to the question “When should I use C?” My answer would be “When you need more control than your current programming language gives you.” Pick one of the Cs if: Pick C if: Pick C++ if: 2.
LIBSVM -- A Library for Support Vector Machines LIBSVM -- A Library for Support Vector Machines Chih-Chung Chang and Chih-Jen Lin Version 3.18 released on April Fools' day, 2014. It conducts some minor fixes. LIBSVM tools provides many extensions of LIBSVM. We now have a nice page LIBSVM data sets providing problems in LIBSVM format. A practical guide to SVM classification is available now! To see the importance of parameter selection, please see our guide for beginners. Using libsvm, our group is the winner of IJCNN 2001 Challenge (two of the three competieions), EUNITE world wide competition on electricity load prediction, NIPS 2003 feature selection challenge (third place), WCCI 2008 Causation and Prediction challenge (one of the two winners), and Active Learning Challenge 2010 (2nd place). Introduction LIBSVM is an integrated software for support vector classification, (C-SVC, nu-SVC), regression (epsilon-SVR, nu-SVR) and distribution estimation (one-class SVM). Our goal is to help users from other fields to easily use SVM as a tool.
CMPH - C Minimal Perfect Hashing Library LDA (Latent Dirichlet Allocation) Content and Keyword Optimizer Enter the keyword and url or content you want to improve. Frequently Asked QuestionsWhat is a Good Score?The onTopic score asks the following question: what is the likelihood that your content will be more related to your keywords than a random document. ShareThis Copy and Paste
evil c This is a collection of strange C (and some Java) constructs. It's probably best not to use them, but you should know why they work. The cast-to-bool operator Node *left, *right; int childCount() { return !! Logical XOR A variation on the above. int xor(int a, int b) { return ! The "goes toward" operator void doStuff(int count) { while(count --> 0) fleh(); } Useless but pretty definitions of BOOLs #define TRUE '/'/'/' #define FALSE '-'-'-' Two (2) readers wrote in to comment that the above is unsafe due to operator precedence. Yes. That is true. If you are doing arithmetic with the above, please seek help. Optimization, the Microsoft way This was found in the 2004 leaked Windows sources __inline BOOL SearchOneDirectory( IN LPSTR Directory, IN LPSTR FileToFind, IN LPSTR SourceFullName, IN LPSTR SourceFilePart, OUT PBOOL FoundInTree ) { // // This was way too slow. The canonical temp-less swap a^=b^=a^=b; Duff's Device for loop unrolling Struct/class offsets int ofs = (int)&((Class*)0)->element; snoob
WDEAF: Web Data Extracting and Analyzing Framework - Home FFTW Home Page Cómo pasar una cadena o matrices de cadenas entre VB y un C de DLL This article demonstrates techniques to perform the following tasks between Visual Basic and a C DLL: Pass a string to a C DLL.Pass (and modify) an array of strings to a C DLL.Return a string from a function within a C DLL. Each of these techniques demonstrates slightly different way of handling strings within a DLL, and the last two require the Control Development Kit, which comes with Visual Basic version 3.0, Professional Edition. There are two parts to each technique demonstrated: the declaration within your Visual Basic code for the C function, and the internals of the C function that process the data being passed, modified, or sent back. Pass a String to a C DLL The declaration for the C function must use ByVal for C to receive a string. C functions typically expect strings to end in a "null character" (binary zero). Declare Sub passOneString Lib "mydll.dll" (ByVal lpszBuf As String) The actual C function looks like this: void __far __pascal __export passOneString(char __far *lpszBuf)
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Clustering - Fuzzy C-means A Tutorial on Clustering Algorithms Introduction | K-means | Fuzzy C-means | Hierarchical | Mixture of Gaussians | Links Fuzzy C-Means Clustering The Algorithm Fuzzy c-means (FCM) is a method of clustering which allows one piece of data to belong to two or more clusters. This method (developed by Dunn in 1973 and improved by Bezdek in 1981) is frequently used in pattern recognition. It is based on minimization of the following objective function: where m is any real number greater than 1, uij is the degree of membership of xi in the cluster j, xi is the ith of d-dimensional measured data, cj is the d-dimension center of the cluster, and ||*|| is any norm expressing the similarity between any measured data and the center. This iteration will stop when , where is a termination criterion between 0 and 1, whereas k are the iteration steps. Remarks As already told, data are bound to each cluster by means of a Membership Function, which represents the fuzzy behaviour of this algorithm. (a) (b) .
VBVM6: A Visual Basic TypeLib for memory access Michel Rutten Pop Quiz Do you…need flexible but efficient memory access in your Visual Basic programs? If you have responded Yes! 1. Techically savvy Visual Basic programmers for long have had to deal with VB's limited type system and lack of support for casting and pointer manipulation. 2. 2.1 Hidden gems All Visual Basic programs require and reference an associated run-time library. Because any VB application per definition requires this dll, any extra functionality we may get out of this library we get for free, i.e. without adding an extra external dependency to the project. Their names suggest that these functions read or write a value of the indicated size from or to memory, offering an interesting prospect at the very least. 2.2 GetMem This is the assembly listing for the GetMem functions: 2.3 PutMem This is the assembly listing for the PutMem functions: The PutMem functions are the counterparts of the GetMem functions. 3. Alternatively one could use: But wait! 4. 4.1 Basic declarations