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Hey sacrpio, your questions all sound like homework problems.
Tell us what you think the answers are, and the nice folks here will give you better help.
typedef is not for defining variables!
typedef is for defining types!
and you can make variables of a certain type (but you can make constants of a certain type too)
#define is a preprocessor statement as said before. It just substitutes the defined stuff in your code. It doesn't show up in the debugger! Try to avoid it as much as possible!!! Writing code in C for microcontrollers is one of the few places where it's actually interesting to use (especially when your compiler doesn't support 'inline' and 'const' doesn't put stuff in flash/rom (or you're short on resources))
hi,
1. #define is used for MACROS. Example: Suppose we have a program where we need to use the value 3.14 many a times and for clarity sake we go for MACROS as
#define PI 3.14
So everytime u can use PI instead of 3.14.You cannot modify the value of PI.U can take it as read-only.
2.Coming to typedef we use it when we define our own datatypes.Structures and enums are user defined data types.Again coming to a math example u want to define your own data type called ComplexNumber you simply say
Code:
typedef struct {
int real;
int img;
}ComplexNumber;
later u can say:
ComplexNumber num1;//(like int i)
without typedef u ll have to say:
struct ComplexNumber num1;
Regards,
Kareja
1> The typedef is limited to giving symbolic names to types only where as #define can be used to define alias for values as well, like you can define 1 as ONE etc.
2> #define should not be terminated with semicolon, but typedef should be terminated with semicolon.
3> #define will just copy-paste the definition values at the point of use, while typedef is actual definition of a new type
1. The typedef is limited to giving symbolic names to types only where as #define can be used to define alias for values as well, like you can define 1 as ONE etc.
2.The typedef interpretation is performed by the compiler where as #define statements are processed by the pre-processor.
3.#define should not be terminated with semicolon, but typedef should be terminated with semicolon.
4.#define will just copy-paste the definition values at the point of use, while typedef is actual definition of a new type
5.typedef follows the scope rule which mean if a new type is defined in a scope(inside a function), then the new type name will only be visible till the scope is there.
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