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Rewriting the code fragment shown in Segment 416, using a
switch statement, improves clarity:
switch (industry) {
case 1: case 5:
trade_pointers[limit]
= (struct trade*) malloc (sizeof (struct trade));
trade_pointers[limit] -> price = price;
trade_pointers[limit] -> number = number;
++limit;
break;
case 0: case 2: case 3: case 4: break;
default: printf ("Industry code %i is unknown!\n", industry);
}
If the industry code is 1, execution begins just after
case 1. Because there are no statements before case 5, you
might think that nothing would happen, but no statements implies no
break statement, so execution falls through to the several
statements, terminated by a break statement, following
case 5.
Thus, trades with an industry code of 1 or 5 lead to the
execution of the same statements. Codes 0, 2, 3, and
4 all lead to the execution of no statements. Other codes lead to a
warning.