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The #undef directive in the C programming language is used to undefine a previously declared macro created using the #define directive.

python

This allows you to remove a macro from the current scope so that its name can be redefined or no longer used in your program.

Macros are global: Macros operate at the preprocessor level, and their scope extends to the entire file where they are defined. Once redefined, the new value will be used wherever that macro appears later in the code.

c

main

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#include <stdio.h>
#define MAX 100

int main() 
{
    printf("MAX = %d\n", MAX); // MAX = 100
    #undef MAX                 // remove macros MAX
    #define MAX 200            // define new macros MAX
    printf("MAX = %d\n", MAX); // MAX = 200
    return 0;
}
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SectionΒ 2. ChapterΒ 4

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book
Cancel Macro

The #undef directive in the C programming language is used to undefine a previously declared macro created using the #define directive.

python

This allows you to remove a macro from the current scope so that its name can be redefined or no longer used in your program.

Macros are global: Macros operate at the preprocessor level, and their scope extends to the entire file where they are defined. Once redefined, the new value will be used wherever that macro appears later in the code.

c

main

copy

              
1234567891011

            
#include <stdio.h>
#define MAX 100

int main() 
{
    printf("MAX = %d\n", MAX); // MAX = 100
    #undef MAX                 // remove macros MAX
    #define MAX 200            // define new macros MAX
    printf("MAX = %d\n", MAX); // MAX = 200
    return 0;
}
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 2. ChapterΒ 4
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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