62 lines
1.6 KiB
Markdown
62 lines
1.6 KiB
Markdown
> 2. The following program fragments illustrate the logical operators. Show the output produced by each, assuming that `i`, `j`, and `k` are `int` variables.
|
|
|
|
a. `i = 10; j = 5;`
|
|
```c
|
|
printf("%d", !i < j);
|
|
|
|
// Expected output: `1`, because `!i` evaluates to 0, and 0 is less than 5, so that expression evaluates to true, or 1.
|
|
```
|
|
|
|
b. `i = 2; j = 1;`
|
|
```c
|
|
printf("%d", !!i + !j);
|
|
|
|
// Expected output: `1`, because !!2 evaluates to 1, and !j evaluates to 0
|
|
```
|
|
|
|
c. `i = 5; j = 0; k = -5;`
|
|
```c
|
|
printf("%d", i && j || k);
|
|
|
|
// Expected output: `1`, because i && j should evaluate to 0, but `0 || 1` should evalulate to true.
|
|
```
|
|
|
|
d. `i = 1; j = 2; k = 3;`
|
|
```c
|
|
printf("%d", i < j || k);
|
|
|
|
// Expected output: `1`
|
|
```
|
|
|
|
> 4. Write a single expression whose value is either `-1`, `0`, or `1` depending on whether `i` is less than, equal to, or greater than `j`, respectively.
|
|
|
|
```c
|
|
/*
|
|
If i < j, the output should be -1.
|
|
If i == j, the output should be zero
|
|
If i > j, the output should be 1.
|
|
*/
|
|
(i > j) - (i < j)
|
|
```
|
|
|
|
> 6. Is the following `if` statement legal?
|
|
```c
|
|
if (n == 1-10)
|
|
printf("n is between 1 and 10\n");
|
|
```
|
|
|
|
Yes the statement is *legal*, but it does not produce the intended effect. It would not produce an output when `n = 5`, because `1-10` evaluates to `-9`, and `-9 != 5`.
|
|
|
|
> 10. What output does the following program fragment produce? (Assume that `i` is an integer variable.)
|
|
```c
|
|
int i = 1;
|
|
switch (i % 3) {
|
|
case 0: printf("zero");
|
|
case 1: printf("one");
|
|
case 2: printf("two");
|
|
}
|
|
```
|
|
|
|
The program would print `onetwo` because each case is missing a `break` statement.
|
|
|
|
> 11. The following table shows the telephone ar |