Programming in C

The if Statement
83
Program 6.8A
Continued
if ( operator == '+' )
printf ("%.2f\n", value1 + value2);
else if ( operator == '-' )
printf ("%.2f\n", value1 - value2);
else if ( operator == '*' )
printf ("%.2f\n", value1 * value2);
else if ( operator == '/' )
if ( value2 == 0 )
printf ("Division by zero.\n");
else
printf ("%.2f\n", value1 / value2);
else
printf ("Unknown operator.\n");
}
return 0;
Program 6.8A
Output
Type in your expression.
123.5 + 59.3
182.80
Program 6.8A Output (Rerun)
Type in your expression.
198.7 / 0
Division by zero.
Program 6.8A Output (Second Rerun)
Type in your expression.
125 $ 28
Unknown operator.
When the operator that is typed in is the slash, for division, another test is made to
determine if value2 is 0. If it is, an appropriate message is displayed at the terminal.
Otherwise, the division operation is carried out and the results are displayed. Pay careful
attention to the nesting of the if statements and the associated else clauses in this case.
The else clause at the end of the program catches any “fall throughs.”Therefore, any
value of operator that does not match any of the four characters tested causes this else
clause to be executed, resulting in the display of “Unknown operator.”