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.
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.
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.
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).
#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.
0 comments:
Post a Comment