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This works by cascading several comparisons. As soon as one of these gives a true result, the following statement or block is executed, and no further comparisons are performed. In the following example we are awarding grades depending on the exam result.
if (result <=100 && result >= 75)
printf("Passed: Grade A\n");
else if (result >= 60)
printf("Passed: Grade B\n");
else if (result >= 45)
printf("Passed: Grade C\n");
else
printf("Failed\n");
In this example, all comparisons test a single variable called result. In other cases, each test may involve a different variable or some combination of tests. The same pattern can be used with more or fewer else if's, and the final alone else may be left out.
It is up to the programmer to devise the correct structure for each programming problem. To better understand the use of if else let us see the example
#include <stdio.h>
int main()
{
int num;
for(num = 0 ; num < 10 ; num = num + 1)
{
if (num == 2)
printf("num is now equal to %d\n", num);
if (num < 5)
printf("num is now %d, which is less than 5\n",
num);
else
printf("num is now %d, which is greater than 4\n",
num);
} /* end of for loop */
return 0;
}
Result of the program
num is now 0, which is less than 5
num is now 1, which is less than 5
num is now equal to 2
num is now 2, which is less than 5
num is now 3, which is less than 5
num is now 4, which is less than 5
num is now 5, which is greater than 4
num is now 6, which is greater than 4
num is now 7, which is greater than 4
num is now 8, which is greater than 4
num is now 9, which is greater than 4 |
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