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Introduction [cont'd]
Input Output Functions [cont'd]
Structures and Unions [cont'd]
# Preprocessor [cont'd]
#undef in # Preprocessor of Programming in C
2015 Views
#undef 
#undef is a preprocessor directive statement. It is used to undefined a defined constants.
Syntax 
#undef defined_variable;
Program
	#include
	#ifdef PI
	#undef PI
	#define PI 3.14
	#else
	#define PI 3.14
	#endif
	void main(){
	   printf("PI = %5.2f",PI);
	}
Output 
PI = 3.14
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# Preprocessor of Programming in C
# Preprocessor of Programming in C
# Preprocessor of Programming in C
# Preprocessor of Programming in C
# Preprocessor of Programming in C
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Structures and Unions of Programming in C
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