#define??How do I use it

[vira-lata]

I have a lab which is asking to use #define. I don't really know how to do it and my book doesn't cover it a lot since we don't use #define anymore. Can anyone help me to begin this lab? Just a quick tip. Thanks

#define DEPOSIT
#define WITHDRAW
#define CHECKBALANCE
#define EXIT

This program asks for the amount to be deposited/withdraw or check the balance. I have to use functions for the options I have. I'm ok with functions. The problem is the #define's. Thanks again

[twm]

Example:

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#define DEPOSIT 0
#define WITHDRAW 1
#define CHECKBALANCE 2
#define EXIT 3


#define replaces a string of text with another string of text, it's set up like so:

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#define STRINGTOREPLACE REPLACEWITH


So in the above example, every occurance of DEPOSIT in your code will be replaced with 0 before the code is compiled. Preprocessing takes place before anything else and makes actual text changes in your source file.

[guest]

can you give me a simple example of how to use the #define?
Something simple so I'll be able to get the idea! Thank you!!!!

[Wizard]

Code: Select all

#include <iostream>
#define you me
using namespace std;

int main() {
int me;
you = 3;
};



Looks like this shouldn't compile. I declare an int called me, then assign an undeclared variable called you. But really, the define replaces you with me at compile time, so it's the same as

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#include <iostream>
using namespace std;

int main() {
int me;
me = 3;
};



[raimo]

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#include <iostream>
#define PRINT ;std::cout<<
#define END ;}
#define FUNCTION int
#define PROCEDURE void
#define BEGIN () {
#define CALL ;
#define SANDBOX ()

PROCEDURE foobar
BEGIN
        PRINT "Nonsense\n"
END

FUNCTION main
BEGIN
        PRINT "Hello World!\n"
        CALL foobar SANDBOX
END


[jgbauman]

@raimo:
That was a very nice exmple of very ugly #define usage ;-)

SCNR

[Guest]

I got the idea!!! THANK YOU GUYS VERY MUCH!

You are the real teachers!! Teach for love and pleasure

[Guest]

@raimo:
That was a very nice exmple of very ugly #define usage

SCNR

I agree. What would be wrong with a simple example:

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#define TESTVAL 20
int main()
{
    int i;
    for (i = 0; i < TESTVAL; i++)
    {
        printf("i=%d \n", i);
    }
    return 0;
}