Different ways to define symbolic constants in C    Caption

  • Traditional way to define symbolic constants (using C pre-processor): 

      #define   PI   3.14159 ;

  • Alternate way to define symbolic constants: 

      int const  PI = 3.14159

  • The keyword const specifies that a variable cannot be modified: 

       PI = 4 ; // Will cause a compile error

Example showing the effect of the keyword const

 

  • Program showing that assignment to a const qualified variable is illegal: 

       int main(int argc, char *argv[])             
   {
      int const a = 4;   // Must initialize a constant at definition 
    
      printf (" a = %d\n", a);
    
      a = 1;         // Compile error - illegal !!!  
    
      printf (" a = %d\n", a);
   }

DEMO: demo/C/set1/const1.c