1. C Programming
Lecture 11

2. The switch Statement
The switch statement is a multiway conditional statement generalizing the if-else statement.

3. switch switch (expression) { case constant1: statement . . . statement
case constant_n: statement
default : statement
} /* end switch */

4. The break Statement
The break statement causes a jump out of a switch statement.
Execution continues after the closing brace of the switch statement.

5. Example Using the switch Statement
switch (val) {
case 1:
++a_cnt;
break;
case 2:
case 3:
++b_cnt;
default:
++other_cnt; }
The val expression must
be of an integer type.
The constant integral
expressions following the
case labels must all be
unique.

6. The Effect of a switch Statement
Evaluate the switch expression.
Go to the case label having a constant value that matches the value of the expression found in step 1.
If a match is not found, go to the default label.
If there is no default label, terminate the switch.
Terminate the switch when a break statement is encountered, or by “falling off the end”.

7. Bell Labs Industrial Programming Style
Follow normal rules of English, where possible.
e.g., put a space after a comma
Put one space on either side of a binary operator.
Indent code in a consistent fashion to indicate flow of control.
Put braces as indicated in the following example:
for (i = 0; i < n; ++i) {
. . . /* indent 3 spaces */ }

8. Student Style Place beginning and ending braces in the same column.
while (i < 10) {
. . . }
Either style for braces is acceptable in our class.

9. Misuse of Relational Operators
int k = 8;
if (2 < k < 7)
printf(“true”); /*true is printed*/
else
printf(“false”);
if (2 < k && k < 7)
printf(“true);
printf(“false”); /*false is printed*/