C Aptitude Questions and answers with explanation.

C Aptitude 1
C program aptitude questions, answers and explanation for interview preparations.
In this site, We discussed various type of C programs, now we are moving into further steps by looking at the c aptitude questions.
This questions and answers are helpful to freshers and job hunters. C interview questions are from various companies and experts.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.
Predict the output or error(s) for the following:

C aptitude 1.1

void main()
{
int const * p=5;
printf("%d",++(*p));
}

Answer: Compiler error: Cannot modify a constant value.

Explanation: p is a pointer to a “constant integer”. But we tried to change the value of the “constant integer”.

C aptitude 1.2

main()
{
char s[ ]="man";
int i;
for(i=0;s[ i ];i++)
printf("n%c%c%c%c",s[ i ],*(s+i),*(i+s),i[s]);
}


Answer: mmmm aaaa nnnn

Explanation: s[i], *(i+s), *(s+i), i[s] are all different ways of expressing the same idea. Generally array name is the base address for that array. Here s is the base address. i is the index number/displacement from the base address. So, indirecting it with * is same as s[i]. i[s] may be surprising. But in the case of C it is same as s[i].

C aptitude 1.3

 main()
{
float me = 1.1;
double you = 1.1;
if(me==you)
printf("I love U");
else
printf("I hate U");
}


Answer: I hate U

Explanation: For floating point numbers (float, double, long double) the values cannot be predicted exactly. Depending on the number of bytes, the precession with of the value represented varies. Float takes 4 bytes and long double takes 10 bytes. So float stores 0.9 with less precision than long double. Rule of Thumb: Never compare or at-least be cautious when using floating point numbers with relational operators (== , >, <, <=, >=,!= ) .

Read more Similar C Programs
Learn C Programming
Recursion
C Interview questions

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

C Program to convert number to words.

Problem Statement

Write a C Program to convert number to words.
Example:
Input: 4562
Output: four thousand five hundred sixty two

Solution

The program takes a number between 0 and 99999 as input. First, we count the total number of digits in the number. This is done by successively dividing the number by 10 until we reach 0. Next we go through each digit in the number and decide what to print based on the value of digit at that position. Digit at a particular position can be obtained by dividing the number by a divider. Divider for a given position is pow(10, (position-1)). We start from the left most position and move right as we identify digit at each position and print relevant words to screen.

In the above example, we first divide the number(4562) by 1000 and get 4. We print four thousand and move on to next digit. The next number to work with can be obtained by num % divider. In this case 4562 % 1000 = 562. We divide this number by 100 (divider for position 3) to get 5. So, we print five hundred and move on to next digit. So forth and so on.

Special case handling

A value of 1 at position 2 and 5 needs special attention. Take these examples. In 23, when we encounter 2 at position 2, we can be print ‘twenty’ without knowing next digit. It will be taken care of next. But in case of 15, when we encounter 1 in position 2, we can’t print anything yet! It could be any number between eleven and nineteen. So, we have to wait till we see the next digit. To keep track of this, we maintain a flag variable which is set to 1 to indicate such a case.

Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

The Program

#include<stdlib.h>
#include<stdio.h>
void main() {
long num, div, n1;
int flag, digit, pos, tot_dig;
printf("\nEnter a number: ");
scanf("%ld", &num);
if(num == 0) {
printf("Zeron\n");
exit(0);
}
if(num > 99999) {
printf("please enter a number between 0 and 100000\n\n");
exit(0);
}
tot_dig = 0;
div = 1;
n1 = num;
while ( n1 > 9 ) {
n1 = n1 / 10;
div = div * 10;
tot_dig++;
}
tot_dig++;
pos = tot_dig;
while ( num != 0 ) {
digit = num / div;
num = num % div;
div = div / 10;
switch(pos) {
case 2:
case 5:
if ( digit == 1 )
flag = 1;
else {
flag = 0;
switch(digit) {
case 2: printf("twenty ");break;
case 3: printf("thirty ");break;
case 4: printf("forty ");break;
case 5: printf("fifty ");break;
case 6: printf("sixty ");break;
case 7: printf("seventy ");break;
case 8: printf("eighty ");break;
case 9: printf("ninty ");
}
}
break;
case 1:
case 4:
if (flag == 1) {
flag = 0;
switch(digit) {
case 0 : printf("ten ");break;
case 1 : printf("eleven ");break;
case 2 : printf("twelve ");break;
case 3 : printf("thirteen ");break;
case 4 : printf("fourteen ");break;
case 5 : printf("fifteen ");break;
case 6 : printf("sixteen ");break;
case 7 : printf("seventeen ");break;
case 8 : printf("eighteen ");break;
case 9 : printf("nineteen ");
}
} else {
switch(digit) {
case 1 : printf("one ");break;
case 2 : printf("two ");break;
case 3 : printf("three ");break;
case 4 : printf("four ");break;
case 5 : printf("five ");break;
case 6 : printf("six ");break;
case 7 : printf("seven ");break;
case 8 : printf("eight ");break;
case 9 : printf("nine ");
}
}
if (pos == 4)
printf("thousand ");
break;
case 3:
if (digit > 0) {
switch(digit) {
case 1 : printf("one ");break;
case 2 : printf("two ");break;
case 3 : printf("three ");break;
case 4 : printf("four ");break;
case 5 : printf("five ");break;
case 6 : printf("six ");break;
case 7 : printf("seven ");break;
case 8 : printf("eight ");break;
case 9 : printf("nine ");
}
printf("hundred ");
}
break;
}
pos--;
}
if (pos == 4 && flag == 0)
printf("thousand");
else if (pos == 4 && flag == 1)
printf("ten thousand");
if (pos == 1 && flag == 1)
printf("ten ");
}
view raw number_to_words.c hosted with ❤ by GitHub

 

Sample Output

Sample output

Read more Similar C Programs

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page.

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link

(c) www.c-program-example.com

C program to merge two arrays.

Arrays in C.
Write a C program to merge two arrays.
In this program we check the elements of arrays A, B and put that elements in the resulted array C in sorted manner.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<conio.h>
void main( )
{
int n,m,i,j,k,c[40],a[20],b[20];
clrscr ();
printf("Enter how many elements for array A?:n");
scanf("%d",&n);
printf ("Enter how many elements for array B?:n");
scanf("%d",&m);
printf("Enter elements for A:-n");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
printf("Enter elements for B:-n");
for(j=0;j<m;j++)
scanf("%d",&b[j]);
i=j=k=0;
while(i<n&&j<m)
{
if(a[i]<b[j])
c[k++]=a[i++];
else
if(a[i]>b[j])
c[k++]=b[j++];
else

{
c[k++]=b[j++];
i++;
j++;
}
}

if(i<n)
{
int t;
for(t=0;t<n;t++)

c[k++]=a[i++];
}
if(j<m)
{
int t;
for(t=0;t<m;t++)
{
c[k++]=b[j++];
}
}
printf("nn Merged Array C:nn")
for(k=0;k<(m+n);k++)
printf("t n %d ",c[k]);
getch();
}
Read more Similar C Programs
Data Structures

Learn C Programming

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

K & R C Chapter 6 Exercise Solutions.

We have already provided solutions to all the exercises in the bookC Programming Language (2nd Edition) popularly known as K & R C book.

In this blog post I will give links to all the exercises from Chapter 6 of the book for easy reference.

Chapter 6: Structures

  1. Exercise 6-1. Our version of getword does not properly handle underscores, string constants, comments, or preprocessor control lines. Write a better version.
    Solution to Exercise 6-1.
  2. Exercise 6-2.Write a program that reads a C program and prints in alphabetical order each group of variable names that are identical in the first 6 characters but different somewhere thereafter. Don’t count words within strings and comments. Make 6 a parameter that can be set from the command line.
    Solution to Exercise 6-2.
  3. Exercise 6-3.Write a cross-referencer that prints a list of all words in a document, and, for each word, a list of the line numbers on which it occurs. Remove noise words like “the,” “and,” and so on.
    Solution to Exercise 6-3.
  4. Exercise 6-4. Write a program that prints the distinct words in its input sorted into decreasing order of frequency of occurrence. Precede each word by its count.
    Solution to Exercise 6-4.
  5. Exercise 6-5. Write a function undef that will remove a name and definition from the table maintained by lookup and install .
    Solution to Exercise 6-5.
  6. Exercise 6-6. Implement a simple version of the #define processor (i.e., no arguments) suitable for use with C programs, based on the routines of this section. You may also find getch and ungetch helpful.
    Solution to Exercise 6-6.
You can purchase the book from here or here.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

C Program to search the linked list.

Data structures using C,
Write c program to search the linked list.
Linked list is a data structure in which the objects are arranged in a linear order. In this program, we sort the list elements in ascending order. Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<conio.h>
#include<malloc.h>
struct l_list
{
int info;
struct link *next;
}
start, *node;

int search(int);
void main()
{
int no,i,item,pos;
clrscr();
start.next=NULL;
node=&start;
printf("How many nodes, you want in linked list? ");
scanf("%d",&no);
printf("");
for(i=0;i<no;i++)
{
node->next=(struct l_list *)malloc(sizeof(struct l_list));
printf("Enter element in node %d: ",i+1);
scanf("%d",&node->info);
node=node->next;
}
node->next=NULL;
printf("Linked list(only with info field) is:");

node=&start;
while(node->next!=NULL)
{
printf("%d ",node->info);
node=node->next;
}
printf("

Enter item to be searched : ");
scanf("%d",&item);
pos=search(item);
if(pos<=no)
printf("Your item is at node %d",pos);
else
printf("Sorry! item is no in linked list.a");
getch();
}

int search(int item)
{
int n=1;
node=&start;
while(node->next!=NULL)
{
if(node->info==item)
break;
else
n++;
node=node->next;
}
return n;
}
Read more Similar C Programs
Data Structures

Learn C Programming

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

C Program to find day of birth from DOB

Problem Statement

Write a C Program to find the day of birth when date of birth is given. For example, if we give 02/04/2107  (02nd April 2017) as input, the program should output that it was a Sunday.

Solution

  1. Pick a year as base year where January 1st falls on a Monday. We are using 1900 as base year in our program.
  2. Then we find the number of years after base year. Day of the week in the beginning of the year shifts by 1 in every non leap year. 365 days -> 52 * 7 + 1. 
  3. Once we know on what day a given year started, we can calculate each month’s starting day.
  4. From there it’s as simple as counting the days and finding which day it is.

In this program we find the day of birth like Monday, Sunday.. when date of birth is given. For a more detailed explanation of the method can be found here Converting a Month-Date-Year to the Day of the Week

The Program

#include<stdio.h>
#include<stdlib.h>
int main() {
int d, m, y, year, month, day, i;
printf("Enter date of birth (DD MM YYYY) :");
scanf("%d %d %d", &d, &m, &y);
if( (d > 31) || (m > 12) || (y < 1900 || y >= 2100) )
{
printf("INVALID INPUT. Please enter a valid date between 1900 and 2100");
exit(0);
}
year = y-1900;
year = year/4;
year = year+y-1900;
switch(m)
{
case 1:
case 10:
month = 1;
break;
case 2:
case 3:
case 11:
month = 4;
break;
case 7:
case 4:
month = 0;
break;
case 5:
month = 2;
break;
case 6:
month = 5;
break;
case 8:
month = 3;
break;
case 9:
case 12:
month = 6;
break;
}
year = year + month;
year = year + d;
/* Need to make sure extra day is not needed in leap year for dates before March */
if(( y > 1900 ) && ( y % 4 == 0 ) && ( m < 2 ) )
year--;
day = year % 7;
switch(day)
{
case 0:
printf("Day is SATURDAY\n");
break;
case 1:
printf("Day is SUNDAY\n");
break;
case 2:
printf("Day is MONDAY\n");
break;
case 3:
printf("Day is TUESDAY\n");
break;
case 4:
printf("Day is WEDNESDAY\n");
break;
case 5:
printf("Day is THURSDAY\n");
break;
case 6:
printf("Day is FRIDAY\n");
break;
}
return 0;
}
view raw day_of_birth.c hosted with ❤ by GitHub

Sample Output

Date of birth to day of birth
Finding day of birth from DOB

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this List of C Programs

(c) www.c-program-example.com

C program to print all the possible permutations of given digits

Write a C program to print all the possible permutations of given digits.
Permutations means possible way of rearranging in the group or set in the particular order.
Example:
Input:1, 2, 3
Output:1 2 3, 1 3 2, 2 1 3, 3 1 2, 2 3 1, 3 2 1
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
int lev=-1,n,val[50],a[50];
void main()
{
int i,j;
clrscr();
printf("Enter how many numbers?n");
scanf("%d",&n);
printf("nEnter %d numbers:nn",n);
for(i=0;i<n;i++)
{
val[i]=0;
j=i+1;
scanf("%dnn",&a[j]);
}
visit(0);
getch();
}
visit(int k)
{
int i;
val[k]=++lev;
if(lev==n)
{
for(i=0;i<n;i++)
printf("%2d",a[val[i]]);
printf(" ");
}
for(i=0;i<n;i++)
if(val[i]==0)
visit(i);
lev--;
val[k]=0;

}
Read more Similar C Programs
Learn C Programming
Recursion
Number System

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

C Program to toss a coin using random function.

Write a c program to toss a coin using random function.
In this Program,We use the rand()%2 function that will compute random integers 0 or 1.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

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

int main(void) {
int toss = 0;
int call = 0;
srand(time(NULL));

toss = rand() % 2;

printf("Say head or tail! press 0 for head and 1 for tail:nn");
scanf("%d", &call);
if(call==0 || call==1)
{
if(toss == call)
{
if(toss==1)
printf("You called it correctly ... it is tailn");
else
printf("You called it correctly ... it is headn");
}
else
{
if(toss==1)
printf("No way ...it is head !n");
else
printf("No way ... it is tail!n");
}
}
else
printf("Invalid call!!!!!nn");
return 0;
}
Read more Similar C Programs
Learn C Programming
Recursion
Number System

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

C program to demonstrate assert macro.

Write a C program to demonstrate assert macro.
assert macro defined in assert.h library. assert is mainly used for debugging. assert function checks the conditions at run time, and program executes only if the assert is true otherwise program aborts and shows the error message.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include <stdio.h>
#include <assert.h>
#include<conio.h>
int main()
{
int num1, num2;
clrscr();
printf("Enter two numbers:nn");
scanf("%d %d", &num1, &num2);
assert(num2 != 0);
printf("%d/%d = %.2fn", num1, num2, num1/(float)num2);
return 0;
}
Read more Similar C Programs
Learn C Programming
Recursion
Number System

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com

C program to implement SJF algorithm.

Write a C program to implement SJF algorithm.
Shortest Job First(SJF) is the CPU scheduling algorithm. In SJF, if the CPU is available it allocates the process which has smallest burst time, if the two process are same burst time it uses FCFS algorithm.Read more about C Programming Language . and read the C Programming Language (2nd Edition) by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<conio.h>

void main()
{
int i,j,n,brust_time[10],start_time[10],end_time[10],wait_time[10],temp,tot;
float avg;
clrscr();
printf("Enter the No. of jobs:nn");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
printf("n n Enter %d process burst time:n",i);
scanf("%d",&brust_time[i]);
}

for(i=1;i<=n;i++)
{
for(j=i+1;j<=n;j++)
{
if(brust_time[i]>brust_time[j])
{
temp=brust_time[i];
brust_time[i]=brust_time[j];
brust_time[j]=temp;
}
}

if(i==1)
{
start_time[1]=0;
end_time[1]=brust_time[1];
wait_time[1]=0;
}

else
{
start_time[i]=end_time[i-1];
end_time[i]=start_time[i]+brust_time[i];
wait_time[i]=start_time[i];
}
}
printf("nn BURST TIME t STARTING TIME t END TIME t WAIT TIMEn");
printf("n ********************************************************n");
for(i=1;i<=n;i++)
{
printf("n %5d %15d %15d %15d",brust_time[i],start_time[i],end_time[i],wait_time[i]);
}
printf("n ********************************************************n");
for(i=1,tot=0;i<=n;i++)
tot+=wait_time[i];
avg=(float)tot/n;
printf("nnn AVERAGE WAITING TIME=%f",avg);
for(i=1,tot=0;i<=n;i++)
tot+=end_time[i];
avg=(float)tot/n;
printf("nn AVERAGE TURNAROUND TIME=%f",avg);
for(i=1,tot=0;i<=n;i++)
tot+=start_time[i];
avg=(float)tot/n;
printf("nn AVERAGE RESPONSE TIME=%fnn",avg);
getch();
}
Read more Similar C Programs
C Basic

Search Algorithms.

You can easily select the code by double clicking on the code area above.

To get regular updates on new C programs, you can Follow @c_program

You can discuss these programs on our Facebook Page. Start a discussion right now,

our page!

Share this program with your Facebook friends now! by liking it

(you can send this program to your friend using this button)

Like to get updates right inside your feed reader? Grab our feed!

To browse more C Programs visit this link
(c) www.c-program-example.com