...prototype and Macros in C ?

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Answer by Harish Kamalapurkar
Submitted on 11/9/2004
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Prototype : Normally function prototypes are declared at the beginning of the main function. The only advantage of writting a prototype is that the compiler can catch the discrepancy if any during the compile time itself. for eg. if i write a prototype as void fun (int); in my main programe if i am writting a statement like { double a; fun (a); } The compiler knows that this is an error and it will flash an error during the compilation itself. So prototypes are mearly ment for the compiler i.e you are telling the compiler about the return value and the type of arguments for the function. MACROS: These are handelled by the preprocessor. Preprocessing is the first step which takes place before compilation. There are several advantages of using macros. They improve the readability, portability and documentability. #define MACRO replacement text This macro will just replace the tag with the replacement text wherever the tag appears in the source file. The important thing for macros is that they dont follow scope rules i.e they can be declared at any place, inside the block, outside the block. The effect starts from the place it is declared.

Answer by gk
Submitted on 4/11/2005
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Macros are similar to functions but have different functionality. When a macro is used, the code is just substituted.. for example #define sum(e,f) (e+f) main() { int r=9,t=8; sum(r,t); } The macro sum(r,t) will be substituted by the statement (r+t). This is not the case with function.. The function call will be executed and will not substituted. when used frequently, macros slows down compilation, but is effective when used with simpler logic. Prototype is to tell the compiler that this function is defined else where after the function call. When a function call appears before its definition, prototype is must or else it give error. If u have further doubt, feel free to post the ques

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Question by Harsha
Submitted on 9/19/2003
Related FAQ: comp.lang.c Answers to Frequently Asked Questions (FAQ List)
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What is prototype and Macros in C ?

Answer by CHARAN
Submitted on 2/23/2004
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HI GUYS WHAT IS HYPO CHECKING??? Macros and function are related in what aspect?

Answer by hisham.s.a
Submitted on 3/22/2004
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macros are preprocessors and prototypes are the definition of a function it is also one kind of preprocessor

Answer by tjnomad
Submitted on 9/27/2004
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macros are pre-process before compile and expanded for the 'C' compiler to operate on and understand.

Answer by rg
Submitted on 10/1/2004
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i do agree

Answer by sarada
Submitted on 3/22/2005
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macros are the preprocessors and prototypes are the declarations for functions to be defined later.

Answer by dhanus
Submitted on 11/1/2005
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what is a null macro?what is the difference between null pointer and null macro

Answer by rafi
Submitted on 5/15/2006
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Macro is combination of one or more statements or instructions to carry out particular task automatically when invoked.

Answer by harioum
Submitted on 6/2/2006
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macro is specially a preprocessor directives. this macro replaced by its function code before the compilation of that function. as #define max 12 define function always strats with # here we can replace max by 12 entire the program.

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