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1. Top results related to what are the function of dictionary in c compiler and editor

   • What are the differences between using pure C with a C compiler and the "C part" of a C++ compiler?

     Top Answer

     Answered Sep 06, 2010 · 33 votes

     There are a lot of minor nitpicks. One that strikes me as being the most obvious is that in C++, you have to cast the return value of malloc. Also structs are automatically typedefed in C++.

     Always use a C compiler for C code, not C++. C++ isn't perfectly compatible with C.

     A few others:

     • In C, declaring void func(); declares a function that hasn't specifed what its arguments are, whereas in C++, void func(); is equivalent to the C void func(void)', taking no arguments;
     • Prototypes are required in C++, whereas it's generally just a warning in C;
     • The type of character constants (like 'a') is int in C and char in C++;
     • The type of string literals is char [] in C and const char [] in C++;
     • Some legitimate variable names in C, like class, are reserved keywords in C++.

     For all those who don't believe me and are downvoting, check out this C code:

     #include <stdlib.h>-int main(int argc, char **argv) { int *i = malloc(sizeof(int));- return 0;}-

     Compilation under gcc is fine, but compilation under g++ gives the following errors:

     test.c: In function `int main(int, char**)':test.c:4: error: invalid conversion from `void*' to `int*'-

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     1/5

   • What are the different between calling constructor and calling function pointer of constructor in C++

     Top Answer

     Answered Jan 28, 2024 · 0 votes

     Calling a constructor and calling a function pointer of a constructor in C++ are very similar in the sense that they are both quite impossible:

     • You cannot call a constructor in C++.
     • You cannot obtain a pointer to a constructor in C++.

     According to the C++ spec about constructors:

     Constructors have no names and cannot be called directly.

     So, in C++, you do not call constructors. The language does that for you when you use the new keyword, when you declare an object on the stack, etc. The expression new MyClass() might look like a constructor invocation, and it does in fact contain a constructor invocation, and so it might be mistaken for a constructor invocation, but that's not what it is; it is a "new expression", which includes, among other things, an invocation of a constructor. But the other things are crucial: you cannot just skip them and directly invoke the constructor.

     Function pointers of constructors do not exist because normally you cannot take the address of a constructor. If you examine the names exported by the DLL, and somehow figure out which name corresponds to the constructor, and use that name to obtain the entry point of that constructor from the DLL, you are cheating: you are doing something which is not normally supported by the language. As a result, you should not attempt to invoke that entry point. A constructor is only supposed to be invoked by the language.

     Also according to the C++ spec:

     A constructor is a special non-static member function of a class.

     (Emphasis mine.)

     A constructor assumes that memory has been allocated, and proceeds to initialize that memory. The language takes care of the memory allocation, but invoking the constructor directly does not. Since a constructor is non-static, it expects an uninitialized this to be passed to it, but you are not allocating any memory and you are not passing anything to the constructor. The result is exactly as expected: a crash.

     And besides, think about it: the constructor could not be internally allocating the memory, because how would it work then if the object was allocated on the stack? And how would it work if the constructor was being invoked by the constructor of a derived class which presumably occupies more memory?

     You can get your DLL to work by using a factory method. A factory method is a public static method which executes new ClassA() and returns the result, or declares ClassA() and returns it by value. Then, obtain the address of the factory method from the DLL, and invoke it.

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     2/5

   • What are the benefits of function pointers in C?

     Top Answer

     Answered Jul 19, 2017 · 3 votes

     • Same as regular typdefs, incredibly useful for 2 and 4. Instead of typing the whole thing, you can now use myFuncDef
     • A function declaration for a function that recieves a function pointer. A function that takes a function pointer of 1. would thus look int add2to3(myFuncDef functionPtr);
     • -
     • A function that takes an int and (probably based on that) returns you a function pointer. Using the typedef it would have looked like myFuncDef functionFactory(int n);

     Without typedefs these chains of pointers to pointers could get incredibly long as can be seen in this question: C syntax for functions returning function pointers

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     3/5

   • What are the hazards of comparing expression of different signedness in C and C++?

     Top Answer

     Answered Sep 12, 2020 · 0 votes

     Integers and unsigned integers have the same amount of bits. However, for the signed integer, because of the way one's complement (and with c++20 two's complement) works, the first bit can be interpreted as a “sign bit“: When it is 1, the number is negative.

     So an unsigned int with a 1 as first bit is a very large number, whereas a signed int with a 1 as first bit is a negative number. Comparing the two numbers will thus not work, which is why you have to provide an explicit conversion.

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   • What are the differences between pointer variable's value & address of normal variable and what are the special purpose of pointers in C?

     Top Answer

     Answered Jun 26, 2017 · 5 votes

     Answering questions in reverse order:

     C does not have array variables....but this is really just working with pointers with an alternative syntax.

     This is incorrect, and you need to toss that bookmark in the trash. It's a common misconception that arrays and pointers are the same thing, but they are not. An array expression will be converted to a pointer expression under most circumstances, and array subscripting is accomplished through pointer arithmetic, but an array object is an actual array, not a pointer.

     If pointer also keeps the variable's address in it and at the same time we can get the variable's address using & sign, can't we do the same task pointer does by deriving the address of any variable? I mean if I don't declare it as pointer and use it as int ptr = &i; in 2nd code snippet and use it as normal variable, what would be the differences?

     That code doesn't illustrate why pointers exist, or why they are useful.

     C actually requires us to use pointers in the following cases:

     • To write to a function's parameters;
     • To track dynamically allocated memory;

     Pointers also make dynamic data structures like trees and lists easy to implement, but they aren't required for it (unless you're using dynamic memory allocation in those structures).

     Writing to a function's parameters

     C passes all function arguments by value; the formal parameter in the function definition is a separate object in memory from the actual parameter in the function call, so any change to the formal parameter is not reflected in the actual parameter. For example, assume the following swap function:

     void swap( int a, int b ) { int t = a; a = b; b = t; }-

     This function exchanges the values in a and b. However, when we call the function as

     int x = 4, y = 5;swap( x, y );-

     the values of x and y won't be updated, because they are different objects than a and b. If we want to update x and y, we have to pass pointers to them:

     swap( &x, &y );-

     and update the function definition as follows:

     void swap( int *a, int *b ) { int t = *a; *a = *b; *b = t; }-

     Instead of swapping the contents of a and b, we swap the contents of the objects that a and b point to. This crops up all the time - think about the scanf function, and how you have to use the & operator on scalar arguments.

     Tracking dynamically allocated memory

     The dynamic memory allocation functions malloc, calloc, and realloc all return pointers to dynamic memory buffers; there's no variable associated with that memory as such.

     char *buffer = malloc( sizeof *buffer * some_length );-

     A pointer is the only way to track that memory.

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2. www.geeksforgeeks.org › implementation-on-map-orImplementation on Map or Dictionary Data Structure in C

   www.geeksforgeeks.org › implementation-on-map-or

   • Cached

   Mar 27, 2023 · Last Updated : 27 Mar, 2023. C programming language does not provide any direct implementation of Map or Dictionary Data structure. However, it doesn’t mean we cannot implement one. In C, a simple way to implement a map is to use arrays and store the key-value pairs as elements of the array .

3. stackoverflow.com › questions › 4384359data structures - Quick Way to Implement Dictionary in C ...

   stackoverflow.com › questions › 4384359

   • Cached

   One of the things which I miss while writing programs in C is a dictionary data structure. What's the most convenient way to implement one in C? I am not looking for performance, but ease of coding it from scratch. I don't want it to be generic either -- something like char* → int will do.

   Code sample

   struct nlist {

     struct nlist *next;

     char *name;

     char *defn;

   };...

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4. People also ask

   Can I create a dictionary in C?

   • You can create anything you want in C. You just won't have native language support for most of it. You can create a dictionary in C, but there is no dictionary built in to the standard C library. A quick search on Google code shows that there are open-source (and generously licensed) C dictionary implementations here and here.

   Do dictionaries exist in C? - Stack Overflow

   stackoverflow.com/questions/9405303/do-dictionaries-exist-in-c

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   Why do I need a compiler?

   • Here is where the compiler you installed earlier comes in handy. The compiler will read the program and translate it into a format closer to the computer’s native language and make your program suitable for execution. You will be able to see the output of your program, which should be Hello, world!.

   The C Programming Handbook for Beginners - freeCodeCamp.org

   www.freecodecamp.org/news/the-c-programming-handbook-for-beginners/

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   How does a compiler read a program?

   • The compiler will read the program and translate it into a format closer to the computer’s native language and make your program suitable for execution. You will be able to see the output of your program, which should be Hello, world!. The compilation of a C program consists of four steps: preprocessing, compilation, assembling, and linking.

   The C Programming Handbook for Beginners - freeCodeCamp.org

   www.freecodecamp.org/news/the-c-programming-handbook-for-beginners/

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   Is C a compiled language?

   • C is a compiled programming language, like Go, Java, Swift, and Rust. Compiled languages are different from interpeted languages, such as PHP, Ruby, Python, and JavaScript. The difference between compiled and interpeted languages is that a compiled language is directly translated to machine code all at once.

   The C Programming Handbook for Beginners - freeCodeCamp.org

   www.freecodecamp.org/news/the-c-programming-handbook-for-beginners/

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5. www.freecodecamp.org › news › the-c-programmingThe C Programming Handbook for Beginners - freeCodeCamp.org

   www.freecodecamp.org › news › the-c-programming

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   Aug 29, 2023 · To get started, open Visual Studio Code and create a new folder for your C program by navigating to "File" -> "Open" -> "New Folder". Give this folder a name, for example, c-practice, and then select "Create" -> “Open". You should now have the c-practice folder open in Visual Studio Code.

6. opensource.com › article › 22A programmer's guide to GNU C Compiler | Opensource.com

   opensource.com › article › 22

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   May 20, 2022 · $ rm a.out hellogcc.o $ ls hellogcc.c Pre-processor. First, start the pre-processor, redirecting its output to hellogcc.i: $ cpp hellogcc.c > hellogcc.i $ ls hellogcc.c hellogcc.i. Take a look at the output file and notice how the pre-processor has included the headers and expanded the macros. Compiler. Now you can compile the code into assembly.

7. www.youtube.com › watchHow to Create a Dictionary in C - YouTube

   www.youtube.com › watch

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   30:15

   The dictionary is an unordered collection of key/value pairs, and one can be implemented in C using a binary search tree. To accomplish this, we will need to utilize concepts of object oriented...

   • Views: 15.8K
   • Author: Eric O Meehan

8. www.freecodecamp.org › news › what-is-a-compiler-in-cWhat is a Compiler? Compilers in C Explained for Beginners

   www.freecodecamp.org › news › what-is-a-compiler-in-c

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   Mar 14, 2022 · It is standardization that helps people agree on how things should be done, whether it is C compilers, car components, or anything else. Standardization can also help people agree on which version of C to use. C compilers are an example. The C compiler has long been considered a fundamental component of software development.

9. csc.ucdavis.edu › ~chaos › coursesPart C: Dictionaries, Arrays, Functions, and Modules - UC Davis

   csc.ucdavis.edu › ~chaos › courses

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   The dictionary is a set of key:value pairs: In [1]: atomic_mass = {'H': 1., 'C': 12, 'S': 32} Then we can add another key:value entry using: In [2]: atomic_mass ['O'] = 16. Let's check what we've created: In [3]: atomic_mass.keys () Out [3]: ['H', 'C', 'S', 'O'] In [4]: atomic_mass.values () Out [4]: [1.0, 12, 32, 16.0]