Fisk University. Introduction to Computer Science II, Spring 2009 Homework on Quiz #2 (Due Friday, Feb 20 th, 2009)

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1 Fisk University Introduction to Computer Science II, Spring 2009 Homework on Quiz #2 (Due Friday, Feb 20 th, 2009) If your answer to a question on the quiz is incorrect, type the program given in the box next to it, if any. All the programs are to be done on a lab computer. Preferably run them at the DOS command prompt. Create a function for each incorrect question and name them q1, q2... Call each function from main(). Write the output of each function in comments inside the function. Q1: Pointers cannot be used to: a. Contain memory addresses. b. Reference values directly. c. Pass an argument by reference. d. Manipulate dynamic data structures. Q2: Pointers may be assigned to which of the following? a. Any integer values. b. An address. c. NULL. d. Both (b) and (c). //Q2 Write a function called q2 and type the following and write the output. int I; int *ptr = NULL; if (ptr == 0) cout << Ptr is NULL = << NULL << endl; ptr = &I; if (ptr == &I) cout << Ptr is = << ptr << endl; Q3: What does the following declaration declare? int *countptr, count; a. Two int variables. b. One pointer to an int and one int variable. c. Two pointers to ints. d. The declaration is invalid. Q4: All of the following could cause a fatal execution-time error except: a. Dereferencing a pointer that has not been assigned to point to a specific address. b. Dereferencing a pointer that has not been initialized properly. c. Dereferencing a null pointer. d. Dereferencing a variable that is not a pointer.

2 //Q4 Write a function called q4 and type the following and write the o/p. int *ptr; cout << Dereferencing an uninitialized pointer << *ptr << endl; ptr = NULL; cout << Dereferencing a NULL pointer << *ptr << endl; Q5: Three of the following expressions have the same value. Which of the following expressions has a value different from the others? a. *&Ptr. b. &*Ptr. c. *Ptr. d. Ptr. // Q5 write function called q5 and type the following and write output. int I = 10; int *ptr = &I; cout << *&ptr = << *&ptr << endl; cout << &*ptr = << &*ptr << endl; cout << ptr = << ptr << endl; Q6: When a compiler encounters a function parameter for a single-subscripted array of the form int a[], it converts the parameter to: a. int a. b. int &a. c. int * a. d. No conversion is necessary. Q7: sizeof: a. Is a binary operator. b. Returns the total number of elements in an array. c. Usually returns a double. d. Returns the total number of bytes in a variable. // Q7 same here. Function q7 double Array[13]; cout << sizeof(array) = << sizeof(array) << endl; cout << Number of elements = << sizeof(array) / sizeof(double) << endl; cout << sizeof pointer to the first element = << sizeof(&array[0]) << endl; Q8: Which of the following gives the number of elements in the int array r[ ]? a. sizeof r. b. sizeof ( *r ). c. sizeof r / sizeof ( int ).

3 d. sizeof ( *r ) / sizeof ( int ). Q9: Which of the following can have a pointer as an operand? a. ++. b. *=. c. %. d. /. Q10: Given that k is an integer array starting at location 2000, kptr is a pointer to k and each integer is stored in 4 bytes of memory, what location does kptr + 3 point to? a b c d Q11: Comparing pointers and performing pointer arithmetic on them is meaningless unless: a. They point to elements of the same array. b. You are trying to compare and perform pointer arithmetic on the values to which they point. c. They point to arrays of equal size. d. They point to arrays of the same type. Q12: Assuming that t is an array and tptr is a pointer to that array, which expression refers to the address of the fourth element? a. *( tptr + 3 ). b. tptr[ 3 ]. c. &t[ 3 ]. d. *( t + 3 ). // Q12 same here. Function q12. const int size = 4; double Array[size] = { 10, 20, 30, 40; int I = 0; for(;i < size;i++) { cout << Address (&Array[i]) = << &Array[i] << endl << Address (Array+ i) = << (Array + i) << endl; << Value = << Array[i] << endl; Q13: Assuming that string1 = "hello" and string2 = "hello world", which of the following returns 0? strncmp behaves just like strcmp but it considers only first N characters. N is passed as the last parameter. a. strcmp( string1, string2 ); b. strcmp( string1, string2, 6 ); c. strncmp( string1, string2, 5 ); d. strncmp( string1, string2, 6 );

4 // Q13 Write a function that calls the above 4 functions and write their output. Q14: What is the output? int main () { int i = 10; if (10 >= i) { int i = 100; bar(&i); bar(&i); void bar(int * ptr) { *ptr = *ptr * *ptr; // Q14 Rewrite function main as q15 and rewrite function bar and write the output in comments in function q15. Q15: Write a function called exchange to swap two doubles using pointers. (2 points) int main () { double p = , q = ; exchange( ); cout << p << q; // This should print // Write the exchange function below this. // Q15 Write function exchange and call it as below. void q15 () { double p = , q = ; exchange( &p, &q); cout << p <<, << q; // This should print , Q16: Why is the following program a bad idea? int * bar (int * ptr) { int i; ptr = &i; return ptr; a. Functions can t return pointers b. Function should not return its argument pointer c. Functions should not return a pointer to its local variable

5 d. None of the above Q17: Given an array and a pointer as shown below, write as many different statements as you can write to access I using the two variables. char name[] = FISK ; char *ptr = name; Q18: Fill in the blanks so that the program prints Success. long M = 1234; M_p = &M; * M_pp = &M_p; if (1234 == M_pp) cout << Success ; // Q18 Rewrite the program as below and write the output. long M = 1234; long *M_p = &M; long ** * M_pp = &M_p; if (1234 == ** M_pp) cout << Success ; Q19: What is the output of the last statement? char name [] = { F, I, S, K, \0, Z, \0 ; cout << name; // This prints FISK char *ptr = &name[strlen(name)]; *ptr = Z ; cout << name; a. FISK b. FISKZ c. FISKZZ d. FISKKZ // Q19 Rewrite the program as function q19 and write the output.