Question 1. (pointer and structures)

What is the output of the following program?

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

struct sample{
   int a;
   int b;
   char name[21];
};

void print_struct (const struct sample *p){
   printf("a : %d\nb : %d\nname : %s\n", p->a, p->b, p->name);
}

int main(){
   struct sample * p = malloc(sizeof(struct sample)*2);
   struct sample *q;
   p->a=10;
   p->b=11;
   strcpy(p->name,"cs240");
   print_struct(p);
   (p+1)->a=12;
   (p+1)->b=13;
   strcpy((p+1)->name,"midterm");
   print_struct((p+1));
   q = (p+strlen((p+5%2)->name)%2);
   print_struct(q);
   return 0;
}

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Question 2. (casts)

What is the output of the following program?

#include <stdio.h>
int main()
{
   char array[10] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'};
   char *cptr = (char *)&array;
   int *iptr = (int *)&array;

   cptr += 2;
   iptr += 2;

   printf("%c\n", *cptr);
   printf("%c\n", *(char *)iptr);

   cptr = (char *)(((int *)cptr) + 1);
   iptr = (int *) (((char *)iptr) + 1);

   printf("%c\n", *cptr);
   printf("%c\n", *(char *)iptr);
}

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Question 3. (pointers)


What are the values of i,j,ptr, *ptr, pptr, and **pptr after
executing the following (write '?' if the value is unknown):

int i = 5, j = 10;
int *ptr;
int **pptr;

ptr = &i;
pptr = &ptr;
*ptr = 3;
**pptr = 7;
ptr = 8;
**pptr = 9;
*ptr = &i;
*ptr = 2

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Question 4. (unions)

Please complete the following program to correctly output a student's grades.

The output should be:
Chemistry: 72/100
Computer Science: 100/100
Underwater Basket Weaving: F



#define PASS_FAIL 1
#define STANDARD 2

typedef union {
       int points; /* out of 100 */
       char pf;    /* 'P' for pass, 'F' for fail */
} grade;

typedef struct {
       int type;
       char name[50];
       grade g;
} course;

void printGrades(course *courses, int numCourses)
{
       int i;
       for(i = 0; i < numCourses; i++)
               if(__________________________________)
                       printf("%s: %i/100\n", courses[i].name, courses[i].g.points);
               else
                       ____________________________________________________________
}

int main()
{
       course cArray[3];

       strcpy(cArray[0].name, "Chemistry");
       strcpy(cArray[1].name, "Computer Science");
       strcpy(cArray[2].name, "Underwater Basket Weaving");

       ________________________
       ________________________
       ________________________

       cArray[0].g.points = 72;
       cArray[1].g.points = 100;
       cArray[2].g.pf = 'F';

       printGrades(cArray, 3);
}


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Question 5. (malloc)


The strcatX function returns a new string by concatenating the two strings provided as arguments. 
Please fill in the missing lines.

char *
strcatX(const char *s1, const char *s2)
{
	char *s = malloc(________________________);
	__________________________
	__________________________
	return s;
}

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Question 6. (function pointers)

What is printed by the following program? Write '?' if it would print garbage.

#include <stdio.h>

void add(int *arg1, int *arg2) { *arg1 += *arg2; }

void mul(int *arg1, int *arg2) { *arg1 *= *arg2; }

void sub(int *arg1, int *arg2) { *arg1 -= *arg2; }

void (*getOp(int op))(int *, int *) { 
  switch(op) {
    case 0: return &add;
    case 1: return &mul;
    default: return &sub;
   }
}

int main() {
  int i;
  int x = 2, y = 3;

  for(i = 0; i < 4; i++) {
   getOp(i % 3)(&x, &y);
   printf("x = %d ... y = %d\n", x, y);
  }
}

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Question 7. (code comprehension)

The following function takes as argument two strings hay and needle. The
function will return 1 if the string needle is contained in the string hay,
or 0 if hay does not contain the string needle. 

Please fill in the missing pieces.  NOTE: Your solution should NOT use any 
string functions such as strcpy, strlen etc.

int contains(char * hay, char * needle) 
{
	int i, j;
	
	// for all positions of hay
	i = 0;
        
        // Have not come to the end of string hay 
	while (________) {  

		// Check if at needle matches at this position in hay
		j = 0;
		while (hay[____] != 0 & needle[___] != 0 && ______________) {
			// Match this character. Go to next one
			__________;
		} 

		if (needle[j]==0) {
			// Found match
			return 1;
		}
                // perform search from next position in hay
		___________;
	}

	return 0;
}

int main(int argc, char **argv) {

	if (argc<3) {
		printf("Usage: contains hay needle\n");
		exit(1);
	}

	if (contains(argv[1], argv[2])) {
		printf("Yes\n");
	}
	else {
		printf("No\n");
	}
}