Defining
Constants
There are two simple ways in C to define constants:
· Using #define pre-processor
· Using const keyword
The #define Pre-processor
Given below is the form to use #define preprocessor to define a constant:
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#define identifier value
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The following example explains it in detail:
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#include <stdio.h>
#define LENGTH 10 #define WIDTH 5 #define NEWLINE '\n' int main() { int area; area = LENGTH * WIDTH;
printf("value of area : %d", area);
printf("%c", NEWLINE); return 0; } |
When the above code is compiled and executed, it produces the following result:
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value of area : 50
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The const Keyword
You can use const prefix to declare constants with a specific type as follows:
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const type variable = value;
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The following example explains it in detail:
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#include <stdio.h>
int main() { const int LENGTH = 10; const int WIDTH = 5; const char NEWLINE = '\n'; int area; area = LENGTH * WIDTH; printf("value of area : %d", area); printf("%c", NEWLINE); return 0; } |
When the above code
is compiled and executed, it produces the following result:
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value of area : 50
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Note that it is a
good programming practice to define constants in CAPITALS.
