CSC_Final_Study_Guide_1 - Preprocessing and Macros-Common...

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Unformatted text preview: Preprocessing and Macros-Common mistakes of dynamic memory allocation:- (header) file inclusion (<stdio.h>)-Use pointer to memory not previously allocated statically or dynamicl- Macro substitution (#define PI 3.14)-Use a pointer to read-only memory (i.e. code)- Conditional compilation (#ifdef DEBUG ... #endif)-Use a pointer to memory that has been freed or deallocated-A preprocessing command is terminated at the end of the line unless continued with a \-Forgetting malloc does not initialize memory (#define PI \-Writing past the end of statically or dynamically allocated memory 3.14)-Freeing dynamically UNallocated memory r * PI == r * 3.14-Dont free the same memory twice #define TWOPI 2*PI Const, Enum, Typedef, Booleans, Bitfields, and Unions-Do not terminate #define by ; or it becomes part of token_sequence-The const keyword indicates to the compiler a value should not change-If a #define contains multiple statements, put the whole thing in braces const float pi = 3.14;-The token_sequence doesnt need to be a valid statement or expression. const struct person person1 = {Nate, 72, 190, M}; #define TIMES2 *2-Pointers or variables can be constant, or both-#define can take parameters or arguments (like functions) char * cp = &c; #define DIAM(radius) 2*PI*(radius) char * const cp = &c; (constant pointer)-You do not have to declare the type of argument for a macro like you do functions...
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This note was uploaded on 04/28/2009 for the course CSC 230 taught by Professor Freeh during the Spring '08 term at N.C. State.

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CSC_Final_Study_Guide_1 - Preprocessing and Macros-Common...

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