declaration

what is the description or meaning of this: for example: class test; class test { ..... }; C++ (like C) was designed to be implementable by a single-pass compiler. Forward references are necessary in cases where the compiler needs to know that a symbol refers to a class before the class is actually defined. The classic example of this is when two classes need to contain pointers to each other. i.e. class B; class A { B* b; }; class B { A* a; }; Without the forward reference to B, the compiler could not successfully parse the definition for A and you can't fix the problem by putting the

I was updating a legacy code base in Java and I found a line like this: Object arg[] = { new Integer(20), new Integer(22) }; That line catched my attention because I am used to this kind of code: Object[] arg = { new Integer(20), new Integer(22) }; The content of the array isn't important here. I'm curious about the brackets next to the variable name versus the brackets next to the class name. I tried in Eclipse (with Java 5) and both lines are valid for the compiler. Is there any difference between those declarations? Both are legal and both work. But placing [] before the array's name is

I thought that JavaScript doesn't have block scope, but function scope, and that declarations are hoisted from their block to the top of their parent functions. However, the following code does not work as expected: function one(a) { console.log("one called for " + a); if (a == 1) { function inner(b) { console.log("inner called for " + b); } inner(123); } inner(456); } one(1); one(2); one(3); The first one(1); call proceeds normally, without any errors, however the execution stops when the second one(2); is called. This behavior is intuitive: the function inner is defined only if a==1 . But

I have a simple function in which an array is declared with size depending on the parameter which is int. void f(int n){ char a[n]; }; int main() { return 0; } This piece of code compiles fine on GNU C++ , but not on MSVC 2005. I get the following compilation errors: .\main.cpp(4) : error C2057: expected constant expression .\main.cpp(4) : error C2466: cannot allocate an array of constant size 0 .\main.cpp(4) : error C2133: 'a' : unknown size What can I do to correct this? (I'm interested in making this work with MSVC,without using new/delete) Jack Klein What you have found it one of the Gnu

When I compile the code below #include<stdio.h> int main() { int a; int a = 10; printf("a is %d \n",a); return 0; } I get an error: test3.c: In function ‘main’: test3.c:6:5: error: redeclaration of ‘a’ with no linkage test3.c:5:5: note: previous declaration of ‘a’ was here But if I make the variable global then it works fine. #include<stdio.h> int a; int a = 10; int main() { printf("a is %d \n",a); return 0; } Why is declaring the same global variable twice not an error, but doing that for a local variable is an error? In C, the statement int a; when made at file scope, is a declaration and a

#include <stdio.h> struct context; struct funcptrs{ void (*func0)(context *ctx); void (*func1)(void); }; struct context{ funcptrs fps; }; void func1 (void) { printf( "1\n" ); } void func0 (context *ctx) { printf( "0\n" ); } void getContext(context *con){ con=?; // please fill this with a dummy example so that I can get this working. Thanks. } int main(int argc, char *argv[]){ funcptrs funcs = { func0, func1 }; context *c; getContext(c); c->fps.func0(c); getchar(); return 0; } I am missing something here. Please help me fix this. Thanks. Try this #include <stdio.h> struct context; struct