Description |
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The conditional expression construction provides a shorthand
way of coding an if...else condition. The difference between the expression
notation and an if...else condition is that the ? : notation is an expression and therefore returns
a value, while an if...else condition is a statement and does not return a
value. The syntax described above is equivalent to
if (exp1)
exp2;
else
exp3;
When a conditional expression is executed, exp1 is evaluated first. If it is true (that is, nonzero) exp2 is evaluated and its result is the value of the conditional
expression. If exp1 is false, exp3 is evaluated and its result is the value of the conditional
expression.
There is no requirement that you put parentheses around the exp1 portion of the conditional expression, but doing
so will improve your code's readability.
Both exp2 and exp3 must be assignment-compatible. If exp2 and exp3 are pointers to different types, then the compiler
issues a warning. The value of a conditional expression is either exp2 or exp3, whichever is selected. The other expression is not
evaluated. The type of the result is the type that would be produced
if exp2 and exp3 were mixed in an expression. For instance, if exp2 is a char and exp3 is a double, the result type will be double regardless
of whether exp2 or exp3 is selected.
Example |
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/* Program name is "conditional_exp_op_example".
This program uses the conditional expression to
see if the user wants to continue adding
numbers. */
#include <stdio.h>
int main(void)
{
int a, b, c, d, again, total;
char answer;
printf("\n");
again = 1;
while (again)
{
printf("Enter four numbers separated by spaces that\n");
printf("you want added together: ");
scanf("%d %d %d %d", &a, &b, &c, &d);
fflush(stdin);
total = a + b + c + d;
printf("\nThe total is: %d\n", total);
printf("Do you want to continue ? ");
scanf("%c", &answer);
again = (answer == 'y' || answer == 'Y') ? 1 : 0;
} /* end while */
}
If you execute this program, you get the following output:
Enter four numbers separated by spaces that
you want added together: 20 30 40 50
The total is: 140
Do you want to continue ? y
Enter four numbers separated by spaces that
you want added together: 1 2 3 4
The total is: 10
Do you want to continue ? n
