What are five advantages to using case structure to program multiple alternative decisions?

Answer 1

1. Switch/case structures yield cleaner, more maintainable code than equivalent nested if..else statements.

2. With if...else statements, the programmer must put the most likely cases first. With switch/case structure, the order of the cases is immaterial.

3. The default switch/case label can be placed anywhere. With if...else, the default must be placed last.

4. Where multiple cases contains common (duplicate) code, omitting the break statement allows execution to fall through to the common code. With if...else, the common code must be duplicated.

5. Switch/case is as fast if not faster than equivalent nested if...else statements. However, modern compilers can optimise nested if...else statements into an equivalent switch/case structure wherever appropriate, thus the speed advantage is much less of a concern these days.

Whenever you have the option of using one or the other, use switch/case if only to make code more readable. However, there will be cases where an if...else may be more readable. For instance, consider the following examples:

void f (const char c) {

if (c>='a' && c<='z') {}

else if (c>='A' && c<='Z') {}

else if (c>='0' && c<='9') {}

else {}

}

void g (const char c) {

switch (c) {

case 'a': case 'b': ... case 'y': case 'z': {} break;

case 'A': case 'B': ... case 'Y': case 'Z': {} break;

case '0': case '1': ... case '8': case '9': {} break;

default: {}

}

}

Typing out all the cases in function g would obviously be tiresome and error prone compared to the succinct statements of function f. However, a good compiler will generate the same code regardless of which function you use, so the choice is simply one of which is the most readable.

Answer 2

One of the advantages of using a case structure is creating logic flows. Other advantages include low CPU overhead and they are easy to understand.