Study Questions 1 - 40

Question 1

What is wrong with the following code?

#include /\*This is a directive line\*/
 main /\* This function will be automatically called\*/ (void/\* I do not have arguments to pass\*/)
 { /\* This is the first line in the program /\* I am so excited to write this program \*/
 printf(“Hello world\n”)}
 /\* Finally I am done with it /\* But I am not sure why it does not work :-( \*/ }

Answer 1

Extra curly bracket. Wrong quotations marks, should be “ not “

Question 2

Which of the following are legal C identifier? 100_bottles, _100_bootles, one-hundred-bottles, one_hundred_bottles, one_hundred_bottles_, one__hundred__bottles, one__hundred__bottles__, If, main, Printf, and while.

Answer 2

Identifier may contain digits, letters and underscores but must only begin with letter or underscore. Keywords cannot be used as identifiers: _100_bootles, one_hundred_bottles, one_hundred_bottles_, one_hundred_bottles, one_hundred_bottles_, main, Printf, are legal apparently :P

Question 3

How many token are there in the following C statement? x=answer=(a*b/++c+6-a%f)/(k);

Answer 3

24 tokens x: Identifier, =: operator, answer: Identifier, =: operator, (: punctuation, a: identifier, *: operator, b: identifier, etc.

Question 4

What is the output of the following C statement? printf(“%6d, %4d\n” , 86, 1040);

Answer 4

%d is a placeholder for integers. %6d indicates 6 figures for the integer. %4d indicates 4 figures for the integer. 86, 1040

Question 5

What is the output of the following C statement? printf(“%12.5e\n”, 30.253) ;

Answer 5

%e placeholder for exponent. %12.5 indicates 12 figures and 5 decimal places. 3.02530e+01

Question 6

What is the output of the following C statement? printf(“%.4f\n”, 83.162) ;

Answer 6

%f is a placeholder for float. %.4f indicates 4 decimal places 83.1620

Question 7

What is the output of the following C statement? printf(“%-6.2g\n”, .0000009979);

Answer 7

1e-06 %g converts it into exponential or fixed decimal.
if it is more than 4 figures, it will show as exponent.
if it is less than 4 decimal places of zeros, it will also show as exponent.
in the example, it has gone back 7 decimal places.

Question 8

Write calls to printf that display a float variable x in the following formats: (a) Exponential notation; left-justified in a field of size 8; one digit after the decimal point. (b) Exponential notation; right-justified in a field of size 10; six digits after the decimal point. (c) Fixed decimal notation; left-justified in a field of size 8; three digits after the decimal point. (d) Fixed decimal notation; right-justified in a field of size 6; no digits after the decimal point.

Answer 8

(a) %-8.1e (b) %10.6e (c) %-8.3f (d) %6.f (inclusion of minus sign indicates left-justified)

Question 9

What is the output of the following C statement? printf(“*%d*\n*%-d*\n*%d*\n*%-d*\n”,123456,123456,-123456,-123456);

Answer 9

*123456*
*123456*
*-123456*
*-123456*

Question 10

What is the output of the following C statement? printf(“*%.10d*\n*%-.10d*\n*%.10d*\n*%-.10d*\n”, 123456,123456,-123456,-123456);

Answer 10

*0000123456*
*0000123456*
*-0000123456*
*-0000123456*

Question 11

What is the output of the following C statement? printf(“*%20d*\n*%-20d*\n*%20d*\n*%-20d*\n”, 123456,123456,-123456,-123456);

Answer 11

* 123456*
*123456 *
* -123456*
*-123456 *

Question 12

What is the output of the following C statement? printf(“*%20.10d*\n*%-20.10d*\n*%20.10d*\n*%-20.10d*\n”, 123456,123456,-123456,-123456);

Answer 12

* 0000123456*
*0000123456 *
* -0000123456*
*-0000123456 *

Question 13

What is the output of the following C program? #include main(void) { float m = 6, n = 6, o = 6, p = 6, q = 6; int i = 3, j = 3; m ++; ++ m; m += n += o -= p *= q /= i %= ++j ; printf(“%f\n%f\n %f\n %f\n %f\n %d\n%d”, m, n, o, p, q, i, j); m += 3 + (n += 3 + (o -= 3 + (p *= 3 + (q /= 3 + (i %= j++))))); printf(“%f %f\n%f %f\n%f %d %d\n”, ++m, n++, –o, p–, ++q, i–, –j); }

Answer 13

Should include otherwise won’t compile. once included. It should produce: 8.000000 0.000000 -6.000000 12.000000 2.000000 3 4-34.000000 -46.000000 -50.000000 40.000000 1.333333 3 4

Question 14

Suppose that we call scanf as follow: scanf (“%d%f%d” , &i, &x, &j); If the user entered 10.3 5 6 what will be the values of i, x, and j after the call? (Assume that i and j are int variables and x is a float variable.)

Answer 14

i will be 10, x will be 5.000000 and j will be 6

Question 15

Suppose that we call scanf as follow: scanf(“%f%d%f”, &x, &i, &y); If the user entered 12.3 45.6 789 what will be the values of x, i, and y after the call? (Assume that x and y are float variables and i is an int variable.)

Answer 15

x will be 12.300000, i will be 45, 789 will be 789.000000

Question 16

For each of the following pairs of scanf format strings, indicate whether or not the two strings are equivalent. If they’re not, show how they can be distinguished. (a) “%d” versus “ %d” (b) “%d-%d-%d” versus “%d -%d -%d” (c) “%f” versus “%f “ (d) “%f,%f” versus “%f, %f”

Answer 16

(a) equivalent (b) equivalent (c) Different, space after %f seems to prompt for another entry, and but only execute the first entry (d) Equivalent

Question 17

Write a program that formats products information entered by the user. A program session should be as follow: Enter item number: 583 Enter unit price: 13.5 Enter purchase date (mm/dd/yyyy): 09/24/2008 Item Unit Purchase Price Date 583 $ 13.50 09/24/2008 The item number and date should be left justified; the unit price should be right justified. Allow dollar amounts up to $9999.99. Hint: Use tabs (i.e., “\t”) to line up the columns.

Answer 17

#include
 main(void)
 {
 int item, mm, dd, yyyy; float price;
 printf("Enter item number: ");
 scanf("%d", &item);
 printf("Enter unit price: ");
 scanf("%f", &price);
 printf("Enter purchase date (mm/dd/yyyy): ");
 scanf("%d/%d/%d", &mm, &dd, &yyyy);
 printf("Item\tUnit\tPurchase\n\tPrice\tdate\n%-d\t%4.2f\t%-.2d/%-.2d/%-.2d\n", item, price, mm, dd, yyyy);
 }

Question 18

Write a program that prompts the user to enter a ten digit telephone number in the form xxxxxxxxxx and then displays the number in the form (xxx) xxx-xxxx.

Answer 18

include <stdio.h><br></br> main(void)<br></br> {<br></br> int phone, phone1, phone2, phone3;<br></br> printf("Enter telephone number: ");<br></br> scanf("%d", &amp;phone);<br></br> phone1 = phone*0.0000001;<br></br> phone2 = (phone - (phone1*10000000))*0.0001;<br></br> phone3 = phone - (phone1*10000000) - (phone2*10000);<br></br> while(phone1 &gt; 999 || phone1 &lt; 100 || phone2 &gt; 999 || phone2 &lt; 100 || phone3 &gt; 9999 || phone3 &lt; 100)<br></br> {<br></br> printf("Invalid number, enter number again: ");<br></br> scanf("%d", &amp;phone);<br></br> phone1 = phone*0.0000001;<br></br> phone2 = (phone - (phone1*10000000))*0.0001;<br></br> phone3 = phone - (phone1*10000000) - (phone2*10000);<br></br> }<br></br> printf("(%d) %d-%d\n", phone1, phone2, phone3);<br></br> }</stdio.h>

Question 19

Write a program that asks the user to enter the numbers from 1 to 16 (in any order) and then displays the numbers in the same order in a 4 by 4 row-wise arrangement, followed by the sums of each rows, each columns, and each diagonals.

Answer 19

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Question 20

Show the output produced by the following program fragment. int i, j; i = 7; j = 8; i *= j + 1; printf(“%d %d\n”, i, j);

Answer 20

63 8

Question 21

Show the output produced by the following program fragment. int i; int j, k; i = j = k = 1; i += j += k; printf(“%d %d %d\n”, i, j, k);

Answer 21

3 2 1

Question 22

Show the output produced by the following program fragment. int i; int j; int k; i = 1; j = 2; k = 3; i -= j -= k; printf(“%d %d %d\n”, i, j, k);

Answer 22

2 -1 3

Question 23

Show the output produced by the following program fragment. int i, j, k; i = 2; j = 1; k = 0; i *= j *= k; printf(“%d %d %d\n”, i, j, k);

Answer 23

0 0 0

Question 24

Show the output produced by the following program fragment. int i, j; i = 6 ; j = i += i; printf(“%d %d”, i, j);

Answer 24

12 12

Question 25

Show the output produced by the following program fragment. int i, j; i = 5 ; j = (i -= 2) + 1; printf(“%d %d”, i, j);

Answer 25

3 4

Question 26

Show the output produced by the following program fragment. int i, j; i = 7 ; j = 6 + (i = 2.5) ; printf(“%d %d”, i, j);

Answer 26

2 8

Question 27

Show the output produced by the following program fragment. int i, j; i = 2; j = 8; j = (i = 6) + (j = 3); printf(“%d %d”, i, j);

Answer 27

6 9

Question 28

Show the output produced by the following program fragment. int i; i = 1 ; printf(“%d “ i++ - 1); print f(“%d”, i);

Answer 28

0 2

Question 29

Show the output produced by the following program fragment. int i, j; i = 10; j = 5; printf(“%d “ i++ - ++j); printf(“%d %d”, i, j),

Answer 29

4 11 6

Question 30

Show the output produced by the following program fragment. int i, j; i = 7 ; j = 8 ; printf(“%d “ i++ - –j); printf(“%d %d”, i, j);

Answer 30

0 8 7

Question 31

Show the output produced by the following program fragment. int i, j, k; i = 3; j = 4; k = 5; printf(“%d “, i++ - j++ + –k); printf(“%d %d %d”, i, j, k);

Answer 31

3 4 5 4

Question 32

. Show the output produced by the following program fragment. int i, j; i = 5; j = ++i * 3 - 2; printf(“%d %d”, i, j);

Answer 32

6 16

Question 33

Show the output produced by the following program fragment. int i, j; i = 5 ; j = 3 - 2 * i++; printf(“%d %d”, i, j);

Answer 33

6 -7

Question 34

Show the output produced by the following program fragment. int i, j; i = 7 ; j = 3 * i– + 2; print f(“%d %d”, i, j);

Answer 34

6 23

Question 35

Show the output produced by the following program fragment. int i, j; i = 7 ; j = 3 + –i * 2; printf(“%d %d”, i, j);

Answer 35

6 15

Question 36

Write a program that computes the volume of a sphere (4/3 π r3), where r is the radius of the sphere. Your program should ask the user to enter the radius of the sphere.

Answer 36

include #include int main(){ float r; float volume; printf(“Enter radius of the sphere : “); scanf(“%f”,&r); volume = (4.0/3) * M_PI * r * r * r; printf(“\nVolume of sphere is : %.3f”,volume); return 0; }

Question 37

Write a program that asks the user to enter a value for x and then displays the value of the following polynomial: 3x^5 + 2x^4 – 5x^3 + x^2 – x – 6

Answer 37

include #include int main(){ float x; float polynomial; printf(“Enter value for x: “); scanf(“%f”,&x); polynomial = (x*x*x*x*x*3)+(x*x*x*x*2)+(x*x*x*5)+(x*x)-x-6; printf(“\npolynomial value is: %.3f”,polynomial); return 0; }

Question 38

Write a program that asks the user to enter a dollar amount and then shows how to pay that amount using the smallest number of $20, $10, $5, $2, and $1.

Answer 38

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Question 39

Write a program that asks the user to enter a two-digit number, then prints the number with its digits reversed. A session with the program should have the following appearance: Enter a two-digit number: 28 The reversal is: 82 Hint: Read the number using %d, then break it into two digits. If n is an integer, then n % 10 is the last digit in n and n / 10 is n with the last digit removed.

Answer 39

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Question 40

Write a program to read a float representing a number of degrees Celsius, and print as a float the equivalent temperature in degrees Fahrenheit. Print your results in a form such as Enter a temperature is Celsius degrees: 100 100.0 degrees Celsius is equivalent to 212.0 degrees Fahrenheit

Answer 40

include #include int main(){ floattemp_c, temp_f; printf (“Enter the value of Temperature in Celcius: “); scanf (“%f”, &temp_c); temp_f = (1.8 * temp_c) + 32; printf (“The value of Temperature in Fahreinheit is: %f”, temp_f); return 0; }