define

c program output

Hello, I am trying some program and confused with the output of the program #include<stdio.h> #define a(x) (x*x) int main() { int i=3,j; j=a(i+1); printf("%d",j); return 0; } I want to know why the program is not giving the output 16(as instead to that i an getting the output 7 for the above program ) i understood the point...

Define data members within constructor

I have got this little snippet of code, I want to be able to define each array element as a new data member. class Core_User { protected $data_members = array( 'id' => '%d', 'email' => '"%s"', 'password' => '"%s"', 'title' => '"%s"', 'first_...

Can you use #defined values in if statements (In C programs)?

I am new at C programming. I thought when you type something like #define Const 5000 that the compiler just replaces every instance of Const with 5000 at compile time. Is that wrong? I try doing this in my code and I get a syntax error. Why can't i do this? #define STEPS_PER_REV 12345 ... in some function if(CurrentPosition >= STEPS_PE...

Why can't I assign a scalar value to a class using shorthand, but instead declare it first, then set its value?

I am writing a UTF-8 library for C++ as an exercise as this is my first real-world C++ code. So far, I've implemented concatenation, character indexing, parsing and encoding UTF-8 in a class called "ustring". It looks like it's working, but two seemingly equivalent ways of declaring a new ustring behave differently. The first way: ustri...

Is there a way to define C inline function in .c file rather than .h file? (Xcode)

As I know, C inline function body should be defined in .h file because it causes an error 'function-name used but never defined" if body defined in .c file. Is this the regular way? Or how to define inline function body in .c file? ...

c++ macros question

can somebody explain the following code please? #if 1 // loop type #define FOR_IS_FASTER 1 #define WHILE_IS_FASTER 0 // indexing type #define PREINCREMENT_IS_FASTER 1 #define POSTINCREMENT_IS_FASTER 0 #else // loop type #define FOR_IS_FASTER 1 #define WHILE_IS_FASTER 0 // indexing type #define PREINCREMENT_IS_FASTER 0 #define POSTINC...

What is the purpose of the #define directive in C++?

What is the role of the #define directive? ...

Is there a config option in PHP to prevent undefined constants from being interpreted as strings?

This is from the php manual: http://us.php.net/manual/en/language.constants.syntax.php If you use an undefined constant, PHP assumes that you mean the name of the constant itself, just as if you called it as a string (CONSTANT vs "CONSTANT"). An error of level E_NOTICE will be issued when this happens. I really don't like this be...

Checking when two headers are included at the same time.

Hi, I need to do an assertion based on two related macro preprocessor #define's declared in different header files... The codebase is huge and it would be nice if I could find a place to put the assertion where the two headers are already included, to avoid polluting namespaces unnecessarily. Checking just that a file includes both exp...

a macro question for c language (#define)

I am reading source code of hoard memory allocator, and in the file of gnuwrapper.cpp, there are the following code #define CUSTOM_MALLOC(x) CUSTOM_PREFIX(malloc)(x) What's the meaning of CUSTOM_PREFIX(malloc)(x)? is CUSTOM_PREFIX a function? But as a function it didn't defined anywhere. If it's variable, then how can we use v...

How to define an Integer bean in Struts 1.x

Hi. How do you instantiate an Integer bean, assigning a value, in the Struts 1.x framework? <bean:define id="index" type="java.lang.Integer" value="0"/> or <bean:define id="index" type="java.lang.Integer" value="${0}"/> Results in a: java.lang.ClassCastException: java.lang.String <bean:define id="index" type="java.lang.Integer" v...

C Preprocessor: #define in C... advice

Hi Guys, I'm making a big C project and I have never come across a situation like this before so, I need your advice. What is your opinion? Is it okay to have the constants defined within conditional preprocessors like I have done below or you advise me to do this some other way? #define NUM_OCTAVES_4 //#define NUM_OCTAVES_5 #ifde...

Template function in define

Hello, I have some template function and I want to call it using define in c++: #define CONFIG(key, type, def) getValue<type>(key, def); Of course, it won't work. Could I make something like this? ...

how do I print a #defined constant in GDB?

As per subject. I have some constants hash defined like so: #define CONST 40 I've set a break point in my program. How do I print the value of that constant? (I know I can just look at the source code, but I want to be sure of it) ...

What's the point of lambda in scheme?

I am learning scheme. I know how to use both lambda and let expressions. However I'm struggling to figure out what the point is of using lambda. Can't you do everything with let that you can with lambda? It would be especially helpful to see an example of a situation where a lambda expression is a better choice than let. One other thi...

Scheme define/lambda shorthand

In Scheme, how can I make use of the define/lambda shorthand for nested lambda expressions within my define? For example given the following procedure... (define add (lambda (num1 num2) (+ num1 num2))) One can shorten it to this: (define (add num1 num2) (+ num1 num2)) However, how can I shorten the following function simi...

Understanding a #define directive

Looking at the Windows SDK, I found this #define directive for MAKEINTRESOURCEW: #define MAKEINTRESOURCEW(i) ((LPWSTR)((ULONG_PTR)((WORD)(i)))) Can someone explain to me what the heck that means? For example, what would be the value of MAKEINTRESOURCEW(0)? (1)? (-1)? ...

Why do all procedures have to be defined before the compiler sees them?

For example, take a look at this code (from tspl4): (define proc1 (lambda (x y) (proc2 y x))) If I run this as my program in scheme... #!r6rs (import (rnrs)) (define proc1 (lambda (x y) (proc2 y x))) I get this error: expand: unbound identifier in module in: proc2 ...This code works fine though: #!r6rs (import (rnr...

How can I define variables in a for loop in javascript?

I'm trying to define variables within a loop. I'll drop the code here and then try and explain some more: for (var k=0; k<nodes.length; k++){ this[node+k] = new google.maps.Marker({ position: new google.maps.LatLng(array1[k], array2[k]), map: map, title: node[k], icon: "some image file" }); } I ...

#define usage in C/C++

I need to write such a define in C/C++ #define scanf( fscanf(inf, in order to replace each scanf( with fscanf(inf, literary But I do not know how... Thanks ...