Question

1. (15 pts) Using the following example,
   int a, p=&a;
   *p = 20;
   Give the two major differences of * and & in the above example.
   
2. (35 pts) Do the following in a program segment step by step. The next step uses the results of the previous step and earlier, using a single statement only and none for manual work.
   1. Declare an array called a of float of size 10 and initialize it to
      2.5, -3.3, 5.9, 1.0, 3.5, 4.3, -7.3, -3.6, 6.1, 2.6
      
      
   2. Declare a point p and initialize it to point to a[2].
      
      
   3. Declare a point q and initialize it to point to a[8].
      
      
   4. Using pointer arithmetic, print the value of a[5] as a line using p but do not change p.
      
      
   5. Increment the pointer q by 1 using ++.
      
      
   6. Manually give the value of p-q. Note: do not use fprint to print it.
      
      
   7. Manually give the value of *q - *p.
      
      
3. (20 pts) Write a function readBetween that takes three parameters, a float array as a pointer p as the first parameter, and two int indices startIdx and endIdx. The function readBetween reads the content of the array between startIdx and endIdx, without using additional local valuables.
   
4. (20 pts) Write a function called tripleOdds that takes two parameters, an array of double pointed to by pointer p and endIdx of int type. The function tripleOdds triples (multiply by 3) every other value in the array (values at 1, 3, 5, …).
   
5. (10 pts) Do the following steps, one step after another.
   1. Using constant directive #define, define string STR_LEN as 50.
      
      
   2. Define string day[5][STR_LEN] and initialize each to “Monday” to “Friday” using five statements, where day[0] is Monday, day[1] is Tuesday, and so on.
      
      

Answer 1

1. 
   int a, p=&a;
   *p = 20;
   two major differences of * and & in the above example.
2. a) * is used to get value at an address whereas & is used to represent an address.
3. b) * is used for pointer variable declaration and & is used for reference variables.

a.

float a[] = {2.5, -3.3, 5.9, 1.0, 3.5, 4.3, -7.3, -3.6, 6.1, 2.6};

b.

float *p = a[2];

c.

float *q = a[8];

d.
printf("%d",*(p+3));

e.
q++;

f.
p-q = 6

g.
*q -*p = 6.1 -5.9 = 0.2

3.

void readBetween(float *p,int startIdx,int endIdx) {

fot(int i = startIdx;i<endIdx;i++)

printf("%f",*(p+i));

}

4.

void tripleOdds(double *p,int endIdx){

for(int i = 0;i<endIdx;i++)

*(p+i) = 3* *(p+i);

}

5

a.
#define STR_LEN 50

b.

string day[5][STR_LEN];

day[0][STR_LEN] = "Monday";

day[0][STR_LEN] = "Tuesday";

day[0][STR_LEN] = "Wednesday";

day[0][STR_LEN] = "Thursday";

day[0][STR_LEN] = "Friday";

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