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- Question
How would you dynamically allocate a 2-D array of integers?
- Correct Answer
- #include "alloch" #define MAXROW 3 #define MAXcol 4 main() { int *p, i, J; p = (int *) malloc (MAXROW * MAXCOL * sizeof (int)); for ( i=0; i < MaxROW ; i++) { for (j=0; j < MAXCOL ; j++) { p [ i * MAXCOL + j] = i; printf ( "%d", p [i * MAXCOL + j] ); } printf ("\n"); } }
- 1. Improve the following code using typedef. struct node { int data1; float data2; struct node *left; struct node *right; }; struct node *ptr; ptr = (struct node *) malloc (sizeof (struct node) ); Discuss
- 2. In the following code can we declare a new typedef name emp even though struct employee has not been completely defined while using typedef? < Yes / No> typedef struct employee *ptr; struct employee { char name[20]; int age; ptr next; }; Discuss
- 3. Answer the following Program #define CHARSIZE 8 #define MASK(y) (1 << y % CHARSIZE) #define BITSLOT (y) (y / CHARSIZE) #define SET(x,y) ( x[BITSLOT(y)] = MASK(y) ) #define TEST(x,y) ( x[BITSLOT(y)] & MASK(y) ) #define NUMSLOTS(n) ((n + CHARSIZE - 1) / CHARSIZE) Give the above macros how would you 1. declare an array arr of 50 bits 2. put the 20th bit on 3. test whether the 40th bit is on or off Discuss
- 4. What would be the output of the following program ? main() { unsigned int a = oxffff; ~a; printf ("%x", a); }
Options- A. ffff
- B. 0000
- C. 00ff
- D. None of the above Discuss
- 5. If the following program (myprog) is run from the command line as myprog 1 2 3 what would be the output? main(int argc, char *argv[]) { int i, j = 0; for (i = 0; i < argc ; i++) j = j + atoi ( argv[i]); printf ("%d", j); }
Options- A. 123
- B. 6
- C. Error
- D. "123" Discuss
- 6. How would you free the memory allocated by the following program? #include "alloc.h" #define MAXROW 3 #define MAXCOL 4 main() { int **p, i; p = (int **) malloc (MAXROW * sizeof (int *)); for ( i = 0; i < MAXROW ; i++) p[i] = (int *) malloc (MAXCOL * sizeof (int )); } Discuss
- 7. Can I increase the size of a dynamically allocated array? < Yes / No> if yes, how? Discuss
- 8. What is the difference between malloc() and calloc() functions? Discuss
- 9. If I use the following printf() to print a long int why I am not warned about the type mismatch? printf ("%d",num ); Discuss
- 10. How would you use qsort() function to sort an array of structures? Discuss
Programming problems
Search Results
Correct Answer: typedef struct node * treeptr typedef struct node { int data1; float data2; treeptr *left; treeptr *right; }treenode; treeptr ptr; ptr = ( treeptr ) malloc ( sizeof ( treenode ) );
Correct Answer: Yes
Correct Answer: 1 char arr[NUMSLOTS(50)]; 2 SET (arr, 20); 3 if (TEST (arr, 40))
Correct Answer: ffff
Correct Answer: 6
Explanation:
When atoi() tries to convert argv[0] to a number it cannot do so (argv[0] being a file name) and hence returns a zero.
Correct Answer: for ( i=0; i < MAXROW ; i++) free (p[i]); free (p);
Correct Answer: Yes, using the realloc() function as shown below: main() { int *p; p = ( int *) malloc (20) ; t = p; t = (int *) realloc ( p, 40); if ( t == NULL ) Printf (" Cannot reallocate, leaves previous allocated region unchanged "); else { if ( p ==t ) ; / * the array expanded at the same region */ else { free ( p ); / * deallocate the original array */ p = t; /* set p to newly allocated region */ } } }
Correct Answer: As against malloc(), calloc() needs two arguments, the number of elements to be allocated and the size of each element For example, p = (int *) calloc (10, sizeof (int)); would allocate space for a 10- integer array Additionally, calloc() would also set each of this element with a value 0 Thus the above call to calloc() is equivalent to: p = (int *) malloc (10 * sizeof (int)); memset (p, 0, 10 * sizeof( int ));
Correct Answer: When a function accepts a variable number of arguments , its prototype cannot provide any information about the number of arguments and type of those variable arguments Hence the compiler cannot warn about the mismatches The programmer must make sure that arguments match or must manually insert explicit typecast
Correct Answer: #include "stringh" #include "stdlibh" struct stud { int rollno; int marks; char name[30]; }; int sort_m (struct stud *, struct stud *); int sort_name (struct stud *, struct stud *); int sort_marks (struct stud *, struct stud *); main() { static struct stud ss[] = { { 15, 96, "Akshay" }, { 2, 97, "Madhuri" }, { 8, 85, "Aishvarya" }, { 10, 80, "Sushmita" } }; int x,w; clrscr(); w = sizeof (struct stud); printf ('\nIn order of roll numbers:"); qsort (ss, 4, w, sort_rn); for(x=0; x<4;x++) printf ("\n%d%s%d", ss[x]rollno, ss[x]name,ss[x]marks); printf("\n\nIn order of names:"); qsort(ss, 4, sort_name); for (x=0; x<4;x++) printf("\n%d%s%d",ss[x]rollno, ss[x]name,ss[x]marks); printf("\n\nIn order of marks:"); qsort(ss,4,w,sort_marks); for (x=0;x<4;x++) printf ("\n%d%s%d",ss[x]rollno,ss[x]name,ss[x]marks); } int sort_rn (struct stud *t1, struct stud *t2) { return (t1->rollno-t2->rollno); } int sort_name (struct stud *t1, struct stud *t2) { return (strcmp(t1->name,t2->name)); } int sort_marks (struct stud *t1, struct stud *t2) { return (t2->marks-t1->marks); }
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