Evaluates its first operand, and, if the resulting value is not equal to zero, evaluates its second operand. Otherwise, it evaluates its third operand, as shown in the following example:
a = b ? c : d;
is equivalent to:
if (b)
a = c;
else
a = d;
This pseudo-code represents it : condition ? value_if_true : value_if_false. Each value can be the result of an evaluated expression.
int x = 5;
int y = 42;
printf("%i, %i\n", 1 ? x : y, 0 ? x : y); /* Outputs "5, 42" */
The conditional operator can be nested. For example, the following code determines the bigger of three numbers:
big= a > b ? (a > c ? a : c)
: (b > c ? b : c);
The following example writes even integers to one file and odd integers to another file:
#include<stdio.h>
int main()
{
FILE *even, *odds; int n = 10;
size_t k = 0;
even = fopen("even.txt", "w");
odds = fopen("odds.txt", "w");
for(k = 1; k < n + 1; k++)
{
k%2==0 ? fprintf(even, "\t%5d\n", k)
: fprintf(odds, "\t%5d\n", k);
}
fclose(even);
fclose(odds);
return 0;
The conditional operator associates from right to left. Consider the following:
exp1 ? exp2 : exp3 ? exp4 : exp5
As the association is from right to left, the above expression is evaluated as
exp1 ? exp2 : ( exp3 ? exp4 : exp5 )
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