0
Still curious? Ask our experts.
Chat with our AI personalities
Blake
Maxine
ViviAdd your answer:
Earn +20 pts
How would you declare a constant of 5 called MYCONST?
A constant of 5 called MYCONST would be declared as #define MYCONST 5. This is because the statement used is a define statement.
Write a preprocessor directive to accomplish Define symbolic constant YES to have the value 1?
I'm not exactly sure that this is a question, but here you are:#define YES 1
Why and when do you use the define directive?
The #define preprocessor directive is severely overused in my opinion. Often, you will see programmers write something like this: # define MAX(a, b) (((a) > (b))? (a) : (b)) However doing so is rather dangerous, because the preprocessor replaces things textually. This means that if you pass in a call to a function, it may happen twice, for example: MAX(++i, j) will be expanded to (((++i) > (j))? (++i) : (j)) which is bad. A much safer (and more common) example is that people will use #define to create a constant variable: #define MYCONST 10 This too can cause problems if another file depends on the constant and certain other conditions are met. A safer alternative is to declare a const variable. The one advantage of using #define for literal constants is that the number will not be stored in memory attached to an object like a const variable will.
What is the effect of this statement in C program define PI 3.14159?
All pre-processor directives begin with a # symbol. One of the most-used pre-processor directives is the #define directive, which has the following syntax:#define SYMBOL definitionThis defines a macro. During preprocessing, all occurrences of SYMBOL within your source code will be replaced with whatever is written in the definition (which includes everything up to the end of the line).#define PI 3.14159Here, all occurrences of the symbol PI within your source code will be replaced with the character sequence 3.14159. So if your source contained the following function:double area_of_circle (double radius) {return 2*PI*radius*radius; // 2 PI r squared}The compiler will see the following instead:double area_of_circle (double radius) { return 2*3.14159*radius*radius;}While this may well seem a convenient method of defining constants, it is not. Macros should never be used to define constants. If you need a constant, use an actual constant. If the constant must be calculated at compile time, then use a constant expression. In this case we can define PI as follows:constexpr double PI (void) {return 4.0 * atan (1.0);}Note that the literal value 3.14159 takes no account of the implementation's precision because the compiler will convert it to a value of 3.141590. By defining the constant expression, the compiler will use a value of 3.14159265359..., including as many digits of precision as the implementation will physically allow, and thus minimising rounding errors.Macros (#defines) should only be used for conditional compilation, never to define constants.
Define social construct?
define social constuction define social constuction
