declaration

问题 Is there a way to do the following at the same time? static final int UN = 0; // uninitialized nodes int[] arr; // ... code ... arr = new int[size]; for (int i = 0; i < 5; i++) { arr[i] = UN; } Basically, I want to declare arr once I know what its size will be and initialize it to UN without having to loop. So something like this: int[] arr = new int[size] = UN; Is this possible? Thanks. 回答1: No, not with the standard libraries. If you write your own functions, though, you can easily do so in

问题 This question is a refinement of my earlier one: How do I write a TypeScript declaration file for an external commonjs module that has constructor? I'm trying to write a declaration file for the imap module: - imap on npm - node-imap What should this file look like? After not finding a satisfactory answer to my original question above, I realize there are some competing features of the language: any export or import makes a module an external module there appears to be no way to export

问题 I'm new to the C language, rather programming overall. I was wondering why is it that when I declare a variable to be used within an if statement OUTSIDE the structure, that the output I've received is incorrect (for this piece of code anyway). Here's my code: #include<stdio.h> void grossPay(); int main() { grossPay(); } void grossPay() { int rate = 10, hours; double tax, grosspay, netpay; printf("Enter work hours this week: "); scanf("%d", &hours); grosspay = hours * rate; if (grosspay <=

问题 This compiles #include "Sprite.h" class GameObject { public: int x, y, w, h; Sprite sprite; public: GameObject(); GameObject(int _x, int _y, int _w, int _h); virtual ~GameObject(); }; This doesn't class Sprite; class GameObject { public: int x, y, w, h; Sprite sprite; public: GameObject(); GameObject(int _x, int _y, int _w, int _h); virtual ~GameObject(); }; I know that I could forward declare and use pointer for Sprite but why doesn't forward declaration works here. Doesn't "class Sprite;"

问题 This is a beginners question but I haven't found a comprehensive answer. What are the differences (if any) of the following declarations? CHARACTER(5) :: a CHARACTER, DIMENSION (5) :: b CHARACTER(LEN=5) :: c CHARACTER :: d(5) CHARACTER :: e*5 And: are all of these declarations possible with other types, e.g REAL ? 回答1: Regardless of the type, <type>,dimension(5) :: b and <type> :: b(5) are identical and denote an array of length 5 . <type> can be e.g. character , integer , real , logical ,

问题 head.h #pragma once namespace foo { int bar; int funct1(); } head.cpp #include "head.h" int foo::funct1() { return bar; } main.cpp #include <iostream> #include "head.h" int main() { foo::bar = 1; std::cout << foo::funct1() << std::endl; return 0; } Error LNK2005 "int foo::bar" (?bar@foo@@3HA) already defined in head.obj I don't understand what is going on. I tried looking for the answer but everyone's questions are so specific to their code and don't even look close to the problem that I am

问题 I'm writing a C compiler, and when I come to the implementation of the switch statement one constraint confused me a lot. Section 6.8.4.2p2 of the standard states: If a switch statement has an associated case or default label within the scope of an identifier with a variably modified type, the entire switch statement shall be within the scope of that identifier. With a footnote: That is, the declaration either precedes the switch statement, or it follows the last case or default label

问题 what's the difference between these 2 declarations: char (*ptr)[N]; vs. char ptr[][N]; thanks. 回答1: (1) declaration char (*ptr)[N]; ptr is pointer to char array of size N following code will help you to on how to use it: #include<stdio.h> #define N 10 int main(){ char array[N] = "yourname?"; char (*ptr)[N] = &array; int i=0; while((*ptr)[i]) printf("%c",(*ptr)[i++]); } output: yourname? See: Codepad (2.A) Where as char ptr[][N]; is an invalid expression gives error: array size missing in 'ptr

问题 Making an unknown friend template<typename T> class List { protected: class a { int x; int y; private: friend class b; // <------------ Why this is not an error? }; template <typename U > class b { //If that is not a error this should be an error int z; U y; }; public: List() { a* ptr = (a *)new unsigned char[sizeof(a)]; } }; int main() { List<int> mylist; } Please go through this link, I have my questions as comments in the code. I am trying to make another class a friend of my class. But

问题 When I compile function with "gcc -o dene -Wall -ansi -pedantic-errors dene.c" ,gcc emits no error.(can you look a line which starts with char ....,in if loop,) static void remove_negation(char *s,char *s1) { char **cmainp=malloc(sizeof(char*)*1); int len=0;int d=0; int i=0; cmainp[0]=malloc(sizeof(char)*300); len=strlen(s); for(i=0;i<len;++i) { if(s[i]=='-') if(i==0 || s[i-1]==',') /*look*/ {char *p=malloc(sizeof(char)*3); /*look*/ ++i; p[0]=s[i]; p[1]='\0'; strcat(s1,","); strcat(s1,p);