C important questions

1. Write a program to find factorial of the given
number.
2. Write a program to check whether the given
number is even or odd.
3. Write a program to swap two numbers using a
temporary variable.
4. Write a program to swap two numbers without
using a temporary variable.
5. Write a program to swap two numbers using
bitwise operators.
6. Write a program to find the greatest of three
numbers.
7. Write a program to find the greatest among ten
numbers.
number is a prime.
number is a palindromic number.
10.Write a program to check whether the given
string is a palindrome.
11.Write a program to generate the Fibonacci series.
12.Write a program to print "Hello World" without

using semicolon anywhere in the code.
13.Write a program to print a semicolon without
using a semicolon anywhere in the code.
14.Write a program to compare two strings without
using strcmp() function.
15.Write a program to concatenate two strings
without using strcat() function.
16.Write a program to delete a specified line from a
text file.
17.Write a program to replace a specified line in a
text file.
18.Write a program to find the number of lines in a
text file.
19.Write a C program which asks the user for a
number between 1 to 9 and shows the number. If the
user
inputs a number out of the specified range, the
program should show an error and prompt the user
for a
valid input.
20.Write a program to display the multiplication
table of a given number.

ANSWERS
1. Write a program to find factorial of the given
number.
Recursion: A function is called 'recursive' if a
statement within the body of a function calls the
same function. It
is also called 'circular definition'. Recursion is thus a
process of defining something in terms of itself.
Program: To calculate the factorial value using
recursion.
#include <stdio.h>
int fact(int n);
int main() {
int x, i;
printf("Enter a value for x: n");
scanf("%d", &x);
i = fact(x);
printf("nFactorial of %d is %d", x, i);
return 0;
} int fact(int n) {
/* n=0 indicates a terminating condition */

if (n <= 0) {
return (1);
} else {
/* function calling itself */
return (n * fact(n - 1));
/*n*fact(n-1) is a recursive expression */
}
}
Output:
Enter a value for x:
4
Factorial of 4 is 24
Explanation:
fact(n) = n * fact(n-1)
If n=4
fact(4) = 4 * fact(3) there is a call to fact(3)
fact(3) = 3 * fact(2)
fact(2) = 2 * fact(1)
fact(1) = 1 * fact(0)
fact(0) = 1
fact(1) = 1 * 1 = 1
fact(2) = 2 * 1 = 2

fact(3) = 3 * 2 = 6
Thus fact(4) = 4 * 6 = 24
Terminating condition(n <= 0 here;) is a must for a
recursive program. Otherwise the program enters
into an
infinite loop.
number is even or odd.
Program:
#include <stdio.h>
int main() {
int a;
printf("Enter a: n");
scanf("%d", &a);
/* logic */
if (a % 2 == 0) {
printf("The given number is EVENn");
}
else {
printf("The given number is ODDn");

}
return 0;
}
Output:
Enter a: 2
The given number is EVEN
Explanation with examples:
Example 1: If entered number is an even number
Let value of 'a' entered is 4
if(a%2==0) then a is an even number, else odd.
i.e. if(4%2==0) then 4 is an even number, else odd.
To check whether 4 is even or odd, we need to
calculate (4%2).
/* % (modulus) implies remainder value. */
/* Therefore if the remainder obtained when 4 is
divided by 2 is 0, then 4 is even. */
4%2==0 is true
Thus 4 is an even number.
Example 2: If entered number is an odd number.
Let value of 'a' entered is 7
if(a%2==0) then a is an even number, else odd.
i.e. if(7%2==0) then 4 is an even number, else odd.

To check whether 7 is even or odd, we need to
calculate (7%2).
7%2==0 is false /* 7%2==1 condition fails and else
part is executed */
Thus 7 is an odd number.
3. Write a program to swap two numbers using a
temporary variable.
Swapping interchanges the values of two given
variables.
Logic:
step1: temp=x;
step2: x=y;
step3: y=temp;
Example:
if x=5 and y=8, consider a temporary variable temp.
step1: temp=x=5;
step2: x=y=8;
step3: y=temp=5;
Thus the values of the variables x and y are
interchanged.

Program:
#include <stdio.h>
int main() {
int a, b, temp;
printf("Enter the value of a and b: n");
scanf("%d %d", &a, &b);
printf("Before swapping a=%d, b=%d n", a, b);
/*Swapping logic */
temp = a;
a = b;
b = temp;
printf("After swapping a=%d, b=%d", a, b);
return 0;
}
Output:
Enter the values of a and b: 2 3
Before swapping a=2, b=3
After swapping a=3, b=2
4. Write a program to swap two numbers without
using a temporary variable.
Swapping interchanges the values of two given
variables.

Logic:
step1: x=x+y;
step2: y=x-y;
step3: x=x-y;
Example:
if x=7 and y=4
step1: x=7+4=11;
step2: y=11-4=7;
step3: x=11-7=4;
Thus the values of the variables x and y are
interchanged.
Program:
#include <stdio.h>
int main() {
int a, b;
printf("Enter values of a and b: n");
scanf("%d %d", &a, &b);
printf("Before swapping a=%d, b=%dn", a,b);
/*Swapping logic */
a = a + b;
b = a - b;
a = a - b;

printf("After swapping a=%d b=%dn", a, b);
return 0;
}
Output:
Enter values of a and b: 2 3
Before swapping a=2, b=3
The values after swapping are a=3 b=2
5. Write a program to swap two numbers using
bitwise operators.
Program:
#include <stdio.h>
int main() {
int i = 65;
int k = 120;
printf("n value of i=%d k=%d before swapping", i,
k);
i = i ^ k;
k = i ^ k;
i = i ^ k;
printf("n value of i=%d k=%d after swapping", i, k);

return 0;
}
Explanation:
i = 65; binary equivalent of 65 is 0100 0001
k = 120; binary equivalent of 120 is 0111 1000
i = i^k;
i... 0100 0001
k...0111 1000
---------
val of i = 001 1 1001
---------
k = i^k
i... 0011 1001
k...0111 1000
---------
val of k = 0100 0001 binary equivalent of this is 65
---------(that is the initial value of i)
i = i^k
i... 0011 1001
k...0100 0001
---------
val of i = 0111 1000 binary equivalent of this is 120

--------- (that is the initial value of k)
6. Write a program to find the greatest of three
numbers.
Program:
#include <stdio.h>
int main(){
int a, b, c;
printf("Enter a,b,c: n");
scanf("%d %d %d", &a, &b, &c);
if (a > b && a > c) {
printf("a is Greater than b and c");
}
else if (b > a && b > c) {
printf("b is Greater than a and c");
}
else if (c > a && c > b) {
printf("c is Greater than a and b");
}
else {
printf("all are equal or any two values are equal");

}
return 0;
}
Output:
Enter a,b,c: 3 5 8
c is Greater than a and b
Consider three numbers a=5,b=4,c=8
if(a>b && a>c) then a is greater than b and c
now check this condition for the three numbers 5,4,8
i.e.
if(5>4 && 5>8) /* 5>4 is true but 5>8 fails */
so the control shifts to else if condition
else if(b>a && b>c) then b is greater than a and c
now checking this condition for 5,4,8 i.e.
else if(4>5 && 4>8) /* both the conditions fail */
now the control shifts to the next else if condition
else if(c>a && c>b) then c is greater than a and b
now checking this condition for 5,4,8 i.e.
else if(8>5 && 8>4) /* both conditions are satisfied
*/
Thus c is greater than a and b.

7. Write a program to find the greatest among ten
numbers.
Program:
#include <stdio.h>
int main() {
int a[10];
int i;
int greatest;
printf("Enter ten values:");
//Store 10 numbers in an array
for (i = 0; i < 10; i++) {
scanf("%d", &a[i]);
}
//Assume that a[0] is greatest
greatest = a[0];
for (i = 0; i < 10; i++) {
if (a[i] > greatest) {
greatest = a[i];
}
}

printf("nGreatest of ten numbers is %d", greatest);
return 0;
}
Output:
Enter ten values: 2 53 65 3 88 8 14 5 77 64 Greatest
of ten numbers is 88
Explanation with example:
Entered values are 2, 53, 65, 3, 88, 8, 14, 5, 77, 64
They are stored in an array of size 10. let a[] be an
array holding these values.
/* how the greatest among ten numbers is found */
Let us consider a variable 'greatest'. At the beginning
of the loop, variable 'greatest' is assinged with the
value of
first element in the array greatest=a[0]. Here
variable 'greatest' is assigned 2 as a[0]=2.
Below loop is executed until end of the array 'a[]';.
for(i=0; i<10; i++)
{
if(a[i]>greatest)
{
greatest= a[i];

}
}
For each value of 'i', value of a[i] is compared with
value of variable 'greatest'. If any value greater than
the value
of 'greatest' is encountered, it would be replaced by
a[i]. After completion of 'for' loop, the value of
variable
'greatest' holds the greatest number in the array. In
this case 88 is the greatest of all the numbers.
number is a prime.
A prime number is a natural number that has only
one and itself as factors. Examples: 2, 3, 13 are
prime
numbers.
Program:
#include <stdio.h>
main() {
int n, i, c = 0;

printf("Enter any number n: n");
scanf("%d", &n);
/*logic*/
for (i = 1; i <= n; i++) {
if (n % i == 0) {
c++;
}
}
if (c == 2) {
printf("n is a Prime number");
}
else {
printf("n is not a Prime number");
}
return 0;
}
Output:
Enter any number n: 7
n is Prime
consider a number n=5
for(i=0;i<=n;i++) /* for loop is executed until the n

value equals i */
i.e. for(i=0;i<=5;i++) /* here the for loop is executed
until i is equal to n */
1st iteration: i=1;i<=5;i++
here i is incremented i.e. i value for next iteration is
2
now if(n%i==0) then c is incremented
i.e.if(5%1==0)then c is incremented, here 5%1=0
thus c is incremented.
now c=1;
2nd iteration: i=2;i<=5;i++
3
i.e.if(5%2==0) then c is incremented, but 5%2!=0
and so c is not incremented, c remains 1
c=1;
3rd iteration: i=3;i<=5;i++
4
i.e.if(5%3==0) then c ic incremented, but 5%3!=0

c=1;
4th iteration: i=4;i<=5;i++
5
i.e. if(5%4==0) then c is incremented, but 5%4!=0
c=1;
6
i.e. if(5%5==0) then c is incremented, 5%5=0 and so
c is incremented.
i.e. c=2
here i value is 6 and 6<=5 is false thus the condition
fails and control leaves the for loop.
now if(c==2) then n is a prime number
we have c=2 from the 5th iteration and thus n=5 is a
Prime number.

number is a palindromic number.
If a number, which when read in both forward and
backward way is same, then such a number is called
a
palindrome number.
Program:
#include <stdio.h>
int main() {
int n, n1, rev = 0, rem;
printf("Enter any number: n");
scanf("%d", &n);
n1 = n;
/* logic */
while (n > 0){
rem = n % 10;
rev = rev * 10 + rem;
n = n / 10;
}
if (n1 == rev){

printf("Given number is a palindromic number");
}
else{
printf("Given number is not a palindromic number");
}
return 0;
}
Output:
Enter any number: 121
Given number is a palindrome
Explanation with an example:
Consider a number n=121, reverse=0, remainder;
number=121
now the while loop is executed /* the condition
(n>0) is satisfied */
/* calculate remainder */
remainder of 121 divided by 10=(121%10)=1;
now reverse=(reverse*10)+remainder
=(0*10)+1 /* we have initialized reverse=0 */
=1
number=number/10
=121/10

=12
now the number is 12, greater than 0. The above
process is repeated for number=12.
remainder=12%10=2;
reverse=(1*10)+2=12;
number=12/10=1;
now the number is 1, greater than 0. The above
process is repeated for number=1.
remainder=1%10=1;
reverse=(12*10)+1=121;
number=1/10 /* the condition n>0 is not
satisfied,control leaves the while loop */
Program stops here. The given number=121 equals
the reverse of the number. Thus the given number is
a
palindrome number.
10.Write a program to check whether the given
string is a palindrome.
Palindrome is a string, which when read in both
forward and backward way is same.

Example: radar, madam, pop, lol, rubber, etc.,
Program:
#include <stdio.h>
#include <string.h>
int main() {
char string1[20];
int i, length;
int flag = 0;
printf("Enter a string: n");
scanf("%s", string1);
length = strlen(string1);
for(i=0;i < length ;i++){
if(string1[i] != string1[length-i-1]){
flag = 1;
break;
}
}
if (flag) {
printf("%s is not a palindromen", string1);
}
else {
printf("%s is a palindromen", string1);

}
return 0;
}
Output:
Enter a string: radar
"radar" is a palindrome
Explanation with example:
To check if a string is a palindrome or not, a string
needs to be compared with the reverse of itself.
Consider a palindrome string: "radar",
---------------------------
index: 0 1 2 3 4
value: r a d a r
---------------------------
To compare it with the reverse of itself, the
following logic is used:
0th character in the char array, string1 is same as 4th
character in the same string.
1st character is same as 3rd character.
2nd character is same as 2nd character.
. . . .
ith character is same as 'length-i-1'th character.

If any one of the above condition fails, flag is set to
true(1), which implies that the string is not a
palindrome.
By default, the value of flag is false(0). Hence, if all
the conditions are satisfied, the string is a
palindrome.
11.Write a program to generate the Fibonacci series.
Fibonacci series: Any number in the series is
obtained by adding the previous two numbers of the
series.
Let f(n) be n'th term.
f(0)=0;
f(1)=1;
f(n)=f(n-1)+f(n-2); (for n>=2)
Series is as follows
011
(1+0)
2 (1+1)
3 (1+2)
5 (2+3)

8 (3+5)
13 (5+8)
21 (8+13)
34 (13+21)
...and so on
Program: to generate Fibonacci Series(10 terms)
#include<stdio.h>
int main() {
//array fib stores numbers of fibonacci series
int i, fib[25];
//initialized first element to 0
fib[0] = 0;
//initialized second element to 1
fib[1] = 1;
//loop to generate ten elements
for (i = 2; i < 10; i++) {
//i'th element of series is equal to the sum of i-1'th
element and i-2'th element.
fib[i] = fib[i - 1] + fib[i - 2];
}
printf("The fibonacci series is as follows n");
//print all numbers in the series

for (i = 0; i < 10; i++) {
printf("%d n", fib[i]);
}
return 0;
}
Output:
The fibonacci series is as follows
01123581
3
21
34
Explanation:
The first two elements are initialized to 0, 1
respectively. Other elements in the series are
generated by looping
and adding previous two numbes. These numbers are
stored in an array and ten elements of the series are
printed as output.
12.Write a program to print "Hello World" without
using semicolon anywhere in the code.

Generally when we use printf("") statement, we have
to use a semicolon at the end. If printf is used inside
an if
Condition, semicolon can be avoided.
Program: Program to print something without using
semicolon (;)
#include <stdio.h>
int main() {
//printf returns the length of string being printed
if (printf("Hello Worldn")) //prints Hello World and
returns 11
{
//do nothing
}
return 0;
}
Output:
Hello World
Explanation:
The if statement checks for condition whether the
return value of printf("Hello World") is greater than
0. printf

function returns the length of the string printed.
Hence the statement if (printf("Hello World")) prints
the string
"Hello World".
13.Write a program to print a semicolon without
using a semicolon anywhere in the code.
Generally when use printf("") statement we have to
use semicolon at the end.
If we want to print a semicolon, we use the
statement: printf(";");
In above statement, we are using two semicolons.
The task of printing a semicolon without using
semicolon anywhere in the code can be
accomplished by using the ascii value of ' ; ' which is
equal to 59.
Program: Program to print a semicolon without
using semicolon in the code.
#include <stdio.h>
int main(void) {
//prints the character with ascii value 59, i.e.,

semicolon
if (printf("%cn", 59)) {
//prints semicolon
}
return 0;
}
Output:
;
Explanation:
If statement checks whether return value of printf
function is greater than zero or not. The return value
of function
call printf("%c",59) is 1. As printf returns the length
of the string printed. printf("%c",59) prints ascii
value that
corresponds to 59, that is semicolon(;).
14.Write a program to compare two strings without
using strcmp() function.
strcmp() function compares two strings
lexicographically. strcmp is declared in stdio.h

Case 1: when the strings are equal, it returns zero.
Case 2: when the strings are unequal, it returns the
difference between ascii values of the characters that
differ.
a) When string1 is greater than string2, it returns
positive value.
b) When string1 is lesser than string2, it returns
negative value.
Syntax:
int strcmp (const char *s1, const char *s2);
Program: to compare two strings.
#include<stdio.h>
#include<string.h>
int cmpstr(char s1[10], char s2[10]);
int main() {
char arr1[10] = "Nodalo";
char arr2[10] = "nodalo";
printf(" %d", cmpstr(arr1, arr2));
//cmpstr() is equivalent of strcmp()
return 0;
}/
/s1, s2 are strings to be compared

int cmpstr(char s1[10], char s2[10]) {
//strlen function returns the length of argument string
passed
int i = strlen(s1);
int k = strlen(s2);
int bigger;
if (i < k) {
bigger = k;
}
else if (i > k) {
bigger = i;
}
else {
bigger = i;
}
//loops 'bigger' times
for (i = 0; i < bigger; i++) {
//if ascii values of characters s1[i], s2[i] are equal do
nothing
if (s1[i] == s2[i]) {
}
//else return the ascii difference

else {
return (s1[i] - s2[i]);
}
}
//return 0 when both strings are same
//This statement is executed only when both strings
are equal
return (0);
}
Output:
-32
Explanation:
cmpstr() is a function that illustrates C standard
function strcmp(). Strings to be compared are sent as
arguments
to cmpstr().
Each character in string1 is compared to its
corresponding character in string2. Once the loop
encounters a
differing character in the strings, it would return the
ascii difference of the differing characters and exit.

15.Write a program to concatenate two strings
without using strcat() function.
strcat(string1,string2) is a C standard function
declared in the header file string.h
The strcat() function concatenates string2, string1
and returns string1.
Program: Program to concatenate two strings
#include<stdio.h>
#include<string.h>
char *strct(char *c1, char *c2);
char *strct(char *c1, char *c2) {
//strlen function returns length of argument string
int i = strlen(c1);
int k = 0;
//loops until null is encountered and appends string
c2 to c1
while (c2[k] != '0') {
c1[i + k] = c2[k];
k++;
}
return c1;

}
int main() {
char string1[15] = "first";
char string2[15] = "second";
char *finalstr;
printf("Before concatenation:"
" n string1 = %s n string2 = %s", string1, string2);
//addresses of string1, string2 are passed to strct()
finalstr = strcat(string1, string2);
printf("nAfter concatenation:");
//prints the contents of string whose address is in
finalstr
printf("n finalstr = %s", finalstr);
//prints the contents of string1
printf("n string1 = %s", string1);
//prints the contents of string2
printf("n string2 = %s", string2);
return 0;
}
Output:
Before concatenation:
string1 = first

string2 = second
After concatenation:
finalstr = firstsecond
string1 = firstsecond
string2 = second
Explanation:
string2 is appended at the end of string1 and
contents of string2 are unchanged.
In strct() function, using a for loop, all the characters
of string 'c2' are copied at the end of c1. return (c1)
is
equivalent to return &c1[0] and it returns the base
address of 'c1'. 'finalstr' stores that address returned
by the
function strct().
16.Write a program to delete a specified line from a
text file.
In this program, user is asked for a filename he
needs to change. User is also asked for the line
number that is

to be deleted. The filename is stored in 'filename'.
The file is opened and all the data is transferred to
another file
except that one line the user specifies to delete.
Program: Program to delete a specific line.
#include <stdio.h>
int main() {
FILE *fp1, *fp2;
//consider 40 character string to store filename
char filename[40];
char c;
int del_line, temp = 1;
//asks user for file name
printf("Enter file name: ");
//receives file name from user and stores in
'filename'
scanf("%s", filename);
//open file in read mode
fp1 = fopen(filename, "r");
c = getc(fp1);
//until the last character of file is obtained
while (c != EOF)

{
printf("%c", c);
//print current character and read next character
c = getc(fp1);
}
//rewind
rewind(fp1);
printf(" n Enter line number of the line to be
deleted:");
//accept number from user.
scanf("%d", &del_line);
//open new file in write mode
fp2 = fopen("copy.c", "w");
c = getc(fp1);
while (c != EOF) {
c = getc(fp1);
if (c == 'n')
temp++;
//except the line to be deleted
if (temp != del_line)
{
//copy all lines in file copy.c

putc(c, fp2);
}
}
//close both the files.
fclose(fp1);
fclose(fp2);
//remove original file
remove(filename);
//rename the file copy.c to original name
rename("copy.c", filename);
printf("n The contents of file after being modified
are as follows:n");
c = getc(fp1);
while (c != EOF) {
printf("%c", c);
c = getc(fp1);
}
fclose(fp1);
return 0;
}
Output:

Enter file name:abc.txt
hi.
Hello
how are you?
I am fine
hope the same
Enter line number of the line to be deleted:4
The contents of file after being modified are as
follows:
hi.
hello
how are you?
hope the same
Explanation:
In this program, user is asked for a filename that
needs to be modified. Entered file name is stored in
a char
array 'filename'. This file is opened in read mode
using file pointer 'fp1'. Character 'c' is used to read
characters
from the file and print them to the output. User is
asked for the line number in the file to be deleted.

The file
pointer is rewinded back and all the lines of the file
except for the line to be deleted are copied into
another file
"copy.c". Now "copy.c" is renamed to the original
filename. The original file is opened in read mode
and the
modified contents of the file are displayed on the
screen.
17.Write a program to replace a specified line in a
text file.
Program: Program to replace a specified line in a
text file.
#include <stdio.h>
int main(void) {
FILE *fp1, *fp2;
//'filename'is a 40 character string to store filename

char filename[40];
char c;
int del_line, temp = 1;
//receives file name from user and stores in
'filename'
c = getc(fp1);
//print the contents of file .
while (c != EOF) {
printf("%c", c);
c = getc(fp1);
}
//ask user for line number to be deleted.
printf(" n Enter line number to be deleted and
replaced");
scanf("%d", &del_line);
//take fp1 to start point.
rewind(fp1);

//open copy.c in write mode
fp2 = fopen("copy.c", "w");
c = getc(fp1);
while (c != EOF) {
if (c == 'n') {
temp++;
}
//till the line to be deleted comes,copy the content
from one file to other
if (temp != del_line){
putc(c, fp2);
}
else //when the line to be deleted comes
{
while ((c = getc(fp1)) != 'n') {
}
//read and skip the line ask for new text
printf("Enter new text");
//flush the input stream
fflush(stdin);
putc('n', fp2);
//put 'n' in new file

while ((c = getchar()) != 'n')
putc(c, fp2);
//take the data from user and place it in new file
fputs("n", fp2);
temp++;
}
//continue this till EOF is encountered
c = getc(fp1);
}
//close both files
fclose(fp1);
fclose(fp2);
//remove original file
remove(filename);
//rename new file with old name opens the file in
read mode
rename("copy.c", filename);
//reads the character from file
c = getc(fp1);
//until last character of file is encountered
while (c != EOF){

printf("%c", c);
//all characters are printed
c = getc(fp1);
}
//close the file pointer
fclose(fp1);
return 0;
}
Output:
hi.
hello
how are you?
hope the same
Enter line number of the line to be deleted and
replaced:4
Enter new text: sayonara see you soon
hi.
hello
how are you?
sayonara see you soon
Explanation:

In this program, the user is asked to type the name of
the file. The File by name entered by user is opened
in
read mode. The line number of the line to be
replaced is asked as input. Next the data to be
replaced is asked. A
new file is opened in write mode named "copy.c".
Now the contents of original file are transferred into
new file
and the line to be modified is deleted. New data is
stored in its place and remaining lines of the original
file are
also transferred. The copied file with modified
contents is replaced with the original file's name.
Both the file
pointers are closed and the original file is again
opened in read mode and the contents of the original
file is
printed as output.
18.Write a program to find the number of lines in a

text file.
Number of lines in a file can be determined by
counting the number of new line characters present.
Program: Program to count number of lines in a file.
#include <stdio.h>
int main()
/* Ask for a filename and count number of lines in
the file*/
{
//a pointer to a FILE structure
FILE *fp;
int no_lines = 0;
//consider 40 character string to store filename
char filename[40], sample_chr;
//receives file name from user and stores in a string
named 'filename'
fp = fopen(filename, "r");
//get character from file and store in sample_chr

sample_chr = getc(fp);
while (sample_chr != EOF) {
//Count whenever sample_chr is 'n'(new line) is
encountered
if (sample_chr == 'n')
{
//increment variable 'no_lines' by 1
no_lines=no_lines+1;
}
//take next character from file.
sample_chr = getc(fp);
}
fclose(fp); //close file.
printf("There are %d lines in %s n", no_lines,
filename);
return 0;
}
Output:
There are 4 lines in abc.txt
Explanation:
In this program, name of the file to be read is taken

as input. A file by the given name is opened in read-
mode
using a File pointer 'fp'. Characters from the file are
read into a char variable 'sample_chr' with the help
of getc
function. If a new line character('n') is encountered,
the integer variable 'no_lines' is incremented. If the
character read into 'sample_char' is not a new line
character, next character is read from the file. This
process is
continued until the last character of the file(EOF) is
encountered. The file pointer is then closed and the
total
number of lines is shown as output.
19.Write a C program which asks the user for a
number between 1 to 9 and shows the number. If the
user inputs a number out of the specified range, the

program should show an error and prompt
the user for a valid input.
Program: Program for accepting a number in a given
range.
#include<stdio.h>
int getnumber();
int main() {
int input = 0;
//call a function to input number from key board
input = getnumber();
//when input is not in the range of 1 to 9,print error
message
while (!((input <= 9) && (input >= 1))) {
printf("[ERROR] The number you entered is out of
range");
//input another number
input = getnumber();
}
//this function is repeated until a valid input is given
by user.
printf("nThe number you entered is %d", input);
return 0;

}/
/this function returns the number given by user
int getnumber() {
int number;
//asks user for a input in given range
printf("nEnter a number between 1 to 9 n");
scanf("%d", &number);
return (number);
}
Output:
Enter a number between 1 to 9
45
[ERROR] The number you entered is out of range
Enter a number between 1 to 9
4
The number you entered is 4
Explanation:
getfunction() function accepts input from user.
'while' loop checks whether the number falls within
range or not
and accordingly either prints the number(If the
number falls in desired range) or shows error

message(number is
out of range).
20.Write a program to display the multiplication
table of a given number.
Program: Multiplication table of a given number
#include <stdio.h>
int main() {
int num, i = 1;
printf("n Enter any Number:");
scanf("%d", &num);
printf("Multiplication table of %d: n", num);
while (i <= 10) {
printf("n %d x %d = %d", num, i, num * i);
i++;
}
return 0;
}
Output:
Enter any Number:5
5 x 1 = 5
5 x 2 = 10
5 x 3 = 15

5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50
Explanation:
We need to multiply the given number (i.e. the
number for which we want the multiplication table)
with value of 'i' which increments from 1 to 10.

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