103 lines
2.7 KiB
Markdown
103 lines
2.7 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.
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a. `i = 10; j = 5;`
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```c
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printf("%d", !i < j);
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// Expected output: `1`, because `!i` evaluates to 0, and 0 is less than 5, so that expression evaluates to true, or 1.
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```
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b. `i = 2; j = 1;`
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```c
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printf("%d", !!i + !j);
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// Expected output: `1`, because !!2 evaluates to 1, and !j evaluates to 0
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```
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c. `i = 5; j = 0; k = -5;`
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```c
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printf("%d", i && j || k);
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// Expected output: `1`, because i && j should evaluate to 0, but `0 || 1` should evalulate to true.
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```
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d. `i = 1; j = 2; k = 3;`
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```c
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printf("%d", i < j || k);
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// Expected output: `1`
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```
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> 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.
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```c
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/*
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If i < j, the output should be -1.
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If i == j, the output should be zero
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If i > j, the output should be 1.
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*/
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(i > j) - (i < j)
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```
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> 6. Is the following `if` statement legal?
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```c
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if (n == 1-10)
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printf("n is between 1 and 10\n");
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```
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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`.
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> 10. What output does the following program fragment produce? (Assume that `i` is an integer variable.)
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```c
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int i = 1;
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switch (i % 3) {
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case 0: printf("zero");
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case 1: printf("one");
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case 2: printf("two");
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}
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```
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The program would print `onetwo` because each case is missing a `break` statement.
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> 11. The following table shows the telephone area codes in the state of Georgia along with the largest city in each area:
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| Area code | Major city |
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| --------- | ---------- |
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| 229 | Albany |
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| 404 | Atlanta |
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| 470 | Atlanta |
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| 478 | Macon |
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| 678 | Atlanta |
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| 706 | Columbus |
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| 762 | Columbus |
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| 770 | Atlanta |
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| 912 | Savannah |
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> Write a switch statement whose controlling expression is the variable `area_code`. If the value of `area_code` is not in the table, the `switch` statement will print the corresponding city name. Otherwise, the `switch` statement will display the message `"Area code not recognized."` Use the techniques discussed in section 5.3 to make the `switch` as simple as possible.
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```c
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int area_code;
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switch (area_code) {
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case 404:
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case 470:
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case 678:
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case 770:
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printf("Atlanta");
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break;
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case 706:
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case 762:
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printf("Columbus");
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break;
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case 229:
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printf("Albany");
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break;
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case 478:
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printf("Macon");
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break;
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case 912:
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printf("Savannah");
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break;
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default:
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printf("Area code not recognized.");
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break;
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}
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``` |