4. Temperature Converter (Symbolic Constants)

In our temperature converter program, we have variables such as “lower,” “upper,” and “step” with certain values. These values have little information when you’re looking back at the code years later. This is why it is important to have meaningful names. A symbolic constant should be used instead.

Symbolic Constant: also called symbolic name, a particular string of characters, defined by “#define name replacement list,” any occurrence of name is replaced by the replacement text

The program below is the modified version of the temperature converter program using symbolic constants.

#include <stdio.h>
#define MIN 0     /* lower limit of table */
#define MAX 300      /* upper limit of table */
#define INCREMENT 50     /* increment */

/* print Fahrenheit-Celsius table */
main(){

  int fahr;
  for (fahr = MIN; fahr <= MAX; fahr = fahr + INCREMENT)
     printf(“%3d %6.1f\n”, fahr, (5.0/9.0)*(fahr-32));

}

“MIN,” “MAX,” and “INCREMENT” are symbolic constants, not variables. Get used to capital letters for symbolic constants and lower case for variables. Also, notice that there is no semi-colon after #define line, this is not a mistake.

constants.

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