C Program to Create a File & Store Information

1. #include <stdio.h>2.  3. void main()4. {5. FILE *fptr;6. char name[20];7. int age;8. float salary;9.  10. /* open for writing */11. fptr = fopen("emp.rec", "w");12.  13. if (fptr == NULL)14. {15. printf("File does not exists \n");16. return;17. }18. printf("Enter the name \n");19. scanf("%s", name);20. fprintf(fptr, "Name = %s\n", name);21. printf("Enter the age\n");22. scanf("%d", &age);23. fprintf(fptr, "Age = %d\n", age);24. printf("Enter the salary\n");25. scanf("%f", &salary);26. fprintf(fptr, "Salary = %.2f\n", salary);27. fclose(fptr);28. }

Output:

Enter the namerajEnter the age40Enter the salary4000000

C Program to Illustrate Reading of Data from a File

1. #include <stdio.h>2. #include <stdlib.h>3.  4. void main()5. {6. FILE *fptr;7. char filename[15];8. char ch;9.  10. printf("Enter the filename to be opened \n");11. scanf("%s", filename);12. /* open the file for reading */13. fptr = fopen(filename, "r");14. if (fptr == NULL)15. {16. printf("Cannot open file \n");17. exit(0);18. }19. ch = fgetc(fptr);20. while (ch != EOF)21. {22. printf ("%c", ch);23. ch = fgetc(fptr);24. }25. fclose(fptr);26. }

C Program Delete a specific Line from a Text File

1. #include <stdio.h>2.  3. int main()4. {5. FILE *fileptr1, *fileptr2;6. char filename[40];7. char ch;8. int delete_line, temp = 1;9.  10. printf("Enter file name: ");11. scanf("%s", filename);12. //open file in read mode13. fileptr1 = fopen(filename, "r");14. ch = getc(fileptr1);15. ` while (ch != EOF)16. {17. printf("%c", ch);18. ch = getc(fileptr1);19. }20. //rewind21. rewind(fileptr1);22. printf(" \n Enter line number of the line to be deleted:");23. scanf("%d", &delete_line);24. //open new file in write mode25. fileptr2 = fopen("replica.c", "w");26. ch = getc(fileptr1);27. while (ch != EOF)28. {29. ch = getc(fileptr1);30. if (ch == '\n')31. temp++;32. //except the line to be deleted33. if (temp != delete_line)34. {35. //copy all lines in file replica.c36. putc(ch, fileptr2);37. }38. }

39. fclose(fileptr1);40. fclose(fileptr2);41. remove(filename);42. //rename the file replica.c to original name43. rename("replica.c", filename);44. printf("\n The contents of file after being modified are as follows:\n");45. fileptr1 = fopen(filename, "r");46. ch = getc(fileptr1);47. while (ch != EOF)48. {49. printf("%c", ch);50. ch = getc(fileptr1);51. }52. fclose(fileptr1);53. return 0;54. }

C Program to Replace a specified Line in a Text File

1. #include <stdio.h>2.  3. int main(void)4. {5. FILE *fileptr1, *fileptr2;6. char filechar[40];7. char c;8. int delete_line, temp = 1;9.  10. printf("Enter file name: ");11. scanf("%s", filechar);12. fileptr1 = fopen(filechar, "r");13. c = getc(fileptr1);14. //print the contents of file .15. while (c != EOF)16. {17. printf("%c", c);18. c = getc(fileptr1);19. }20. printf(" \n Enter line number to be deleted and replaced");21. scanf("%d", &delete_line);

22. //take fileptr1 to start point.23. rewind(fileptr1);24. //open replica.c in write mode25. fileptr2 = fopen("replica.c", "w");26. c = getc(fileptr1);27. while (c != EOF)28. {29. if (c == 'n')30. {31. temp++;32. }33. //till the line to be deleted comes,copy the content to other34. if (temp != delete_line)35. {36. putc(c, fileptr2);37. }38. else39. {40. while ((c = getc(fileptr1)) != 'n')41. {42. }43. //read and skip the line ask for new text44. printf("Enter new text");45. //flush the input stream46. fflush(stdin);47. putc('n', fileptr2);48. //put 'n' in new file49. while ((c = getchar()) != 'n')50. putc(c, fileptr2);51. //take the data from user and place it in new file52. fputs("n", fileptr2);53. temp++;54. }55. //continue this till EOF is encountered56. c = getc(fileptr1);57. }58. fclose(fileptr1);59. fclose(fileptr2);60. remove(filechar);61. rename("replica.c", filechar);62. fileptr1 = fopen(filechar, "r");63. //reads the character from file

64. c = getc(fileptr1);65. //until last character of file is encountered66. while (c != EOF)67. {68. printf("%c", c);69. //all characters are printed70. c = getc(fileptr1);71. }72. fclose(fileptr1);73. return 0;74. }

C Program to Find the Number of Lines in a Text File

1. #include <stdio.h>2.  3. int main()4. {5. FILE *fileptr;6. int count_lines = 0;7. char filechar[40], chr;8.  9. printf("Enter file name: ");10. scanf("%s", filechar);11. fileptr = fopen(filechar, "r");12. //extract character from file and store in chr13. chr = getc(fileptr);14. while (chr != EOF)15. {16. //Count whenever new line is encountered17. if (chr == 'n')18. {19. count_lines = count_lines + 1;20. }21. //take next character from file.22. chr = getc(fileptr);23. }24. fclose(fileptr); //close file.25. printf("There are %d lines in %s in a file\n", count_lines, filechar);26. return 0;

27. }1. C Program to Append the Content of File

at the end of Another#include <stdio.h>

2. #include <stdlib.h>3.  4. main()5. {6. FILE *fsring1, *fsring2, *ftemp;7. char ch, file1[20], file2[20], file3[20];8.  9. printf("Enter name of first file ");10. gets(file1);11. printf("Enter name of second file ");12. gets(file2);13. printf("Enter name to store merged file ");14. gets(file3);15. fsring1 = fopen(file1, "r");16. fsring2 = fopen(file2, "r");17. if (fsring1 == NULL || fsring2 == NULL)18. {19. perror("Error has occured");20. printf("Press any key to exit...\n");21. exit(EXIT_FAILURE);22. }23. ftemp = fopen(file3, "w");24. if (ftemp == NULL)25. {26. perror("Error has occures");27. printf("Press any key to exit...\n");28. exit(EXIT_FAILURE);29. }30. while ((ch = fgetc(fsring1)) != EOF)31. fputc(ch, ftemp);32. while ((ch = fgetc(fsring2) ) != EOF)33. fputc(ch, ftemp);34. printf("Two files merged %s successfully.\n", file3);35. fclose(fsring1);36. fclose(fsring2);37. fclose(ftemp);38. return 0;

39. }

C Program that Merges Lines Alternatively from 2 Files & Print Result

1. #include<stdio.h>2. main()3. {4. char file1[10], file2[10];5.  6. puts("enter the name of file 1"); /*getting the names of file to be

concatenated*/7. scanf("%s", file1);8. puts("enter the name of file 2");9. scanf("%s", file2);10. FILE *fptr1, *fptr2, *fptr3;11. fptr1=fopen(file1, "r"); /*opening the files in read only

mode*/12. fptr2=fopen(file2, "r");13. fptr3=fopen("merge2.txt", "w+"); /*opening a new file in

write,update mode*/14. char str1[200];15. char ch1, ch2;16. int n = 0, w = 0;17. while (((ch1=fgetc(fptr1)) != EOF) && ((ch2 = fgetc(fptr2)) !=

EOF))18. {19. if (ch1 != EOF) /*getting lines in alternately from two

files*/20. {21. ungetc(ch1, fptr1);22. fgets(str1, 199, fptr1);23. fputs(str1, fptr3);24. if (str1[0] != 'n')25. n++; /*counting no. of lines*/26. }27. if (ch2 != EOF)28. {29. ungetc(ch2, fptr2);30. fgets(str1, 199, fptr2);31. fputs(str1, fptr3);

32. if (str1[0] != 'n')33. n++; /*counting no.of lines*/34. }35. }36. rewind(fptr3);37. while ((ch1 = fgetc(fptr3)) != EOF) /*countig no.of words*/38. {39. ungetc(ch1, fptr3);40. fscanf(fptr3, "%s", str1);41. if (str1[0] != ' ' || str1[0] != 'n')42. w++;43. }44. fprintf(fptr3, "\n\n number of lines = %d n number of words is = %d\n",

n, w - 1);45. /*appendig comments in the concatenated file*/46. fclose(fptr1);47. fclose(fptr2);48. fclose(fptr3);49. }

C program to read numbers from a file and write even, odd and prime numbers in separate files  #include <stdio.h>  int main() {        FILE *fp1, *fp2, *fp3, *fp4;        int n, i, num, flag = 0;

        /* open data.txt in read mode */        fp1 = fopen("data.txt", "w");        printf("Enter the value for n:");        scanf("%d", &n);        for (i = 0; i <= n; i++)                fprintf(fp1, "%d ", i);        fprintf(fp1, "\n");        fclose(fp1);

        /* open files to write even, odd and prime nos separately */        fp1 = fopen("data.txt", "r");        fp2 = fopen("even.txt", "w");        fp3 = fopen("odd.txt", "w");        fp4 = fopen("prime.txt", "w");

        fprintf(fp2, "Even Numbers:\n");        fprintf(fp3, "Odd Numbers:\n");        fprintf(fp4, "Prime Numbers:\n");

        /* print even, odd and prime numbers in separate files */

        while (!feof(fp1)) {                fscanf(fp1, "%d", &num);                if (num % 2 == 0) {                        fprintf(fp2, "%d ", num);                } else {                        if (num > 1) {                                for (i = 2; i < num; i++) {                                        if (num % i == 0) {                                                flag = 1;                                                break;                                        }                                }                                if (!flag) {                                        fprintf(fp4, "%d ", num);                                }                        }                        fprintf(fp3, "%d ", num);                        flag = 0;                }        }        fprintf(fp2, "\n");        fprintf(fp3, "\n");        fprintf(fp4, "\n");

        /* close all opened files */        fclose(fp1);        fclose(fp2);        fclose(fp3);        fclose(fp4);        return 0;  }