Programs
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.
8. Write a program to
check whether the given number is a prime.
9. Write a program to
check whether the given 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.
2.
Write a program to check whether the given 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 EVEN\n");
}
else {
printf("The
given number is ODD\n");
}
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=%d\n", a,b);
/*Swapping logic */
a = a + b;
b = a - b;
a = a - b;
printf("After
swapping a=%d b=%d\n", 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 = 0011 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
Explanation
with examples:
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.
8.
Write a program to check whether the given 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
Explanation
with examples:
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++
here i is incremented
i.e. i value for next iteration is 3
now if(n%i==0) then c
is incremented
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++
here i is incremented
i.e. i value for next iteration is 4
now if(n%i==0) then c
is incremented
i.e.if(5%3==0) then c
ic incremented, but 5%3!=0 and so c is not incremented, c remains 1
c=1;
4th iteration:
i=4;i<=5;i++
here i is incremented
i.e. i value for next iteration is 5
now if(n%i==0) then c
is incremented
i.e. if(5%4==0) then
c is incremented, but 5%4!=0 and so c is not incremented, c remains 1
c=1;
5th iteration:
i=5;i<=5;i++
here i is incremented
i.e. i value for next iteration is 6
now if(n%i==0) then c
is incremented
i.e. if(5%5==0) then
c is incremented, 5%5=0 and so c is incremented.
i.e. c=2
6th iteration:
i=6;i<=5;i++
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.
9.
Write a program to check whether the given 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 palindrome\n", string1);
}
else {
printf("%s is a
palindrome\n", 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 some thing with out using semicolon(;)
#include
<stdio.h>
int main() {
//printf returns the
length of string being printed
if
(printf("Hello World\n")) //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("%c\n", 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 =
strct(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");
fp1 = fopen(filename,
"r");
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;
//asks user for file
name
printf("Enter
file name: ");
//receives file name
from user and stores in 'filename'
scanf("%s",
filename);
fp1 = fopen(filename,
"r");
//open file in read
mode
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);
fp1 = fopen(filename,
"r");
//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:
Enter file
name:abc.txt
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;
//asks user for file
name
printf("Enter
file name: ");
//receives file name
from user and stores in a string named 'filename'
scanf("%s",
filename);
//open file in read
mode
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:
Enter file
name:abc.txt
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.
End
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