CBSE Class 12 Computer Science Data File Handling In C++ Notes

If the function modify( ) modifies a record in the file “ item.dat “ with the values of item x passed as argument, write the appropriate parameter for the missing parameter in the above code, so as to modify record at its proper place.
Ans.1. File.seekp((recordsRead-1)*sizeof(x),ios::beg); or File.seekp(-1*sizeof(x),ios::cur);

General program structure used for operating a Text File

                                                                  2 Marks Questions

Text files in input mode:

Write a function in a C++ to count the number of lowercase alphabets present in a text file “BOOK.txt”.

int countalpha()
{            ifstream Fin(“BOOK.txt”);
              char ch;
              int count=0;
              while(!Fin.eof())
                             {Fin.get(ch);
                             if (islower(ch))
                              count++;
                             }

                   Fin.close();

                   return count;

 }

Function to calculate the average word size of a text file.

        void calculate()

       {    fstream File;

             File.open(“book.txt”,ios::in);

             char a[20];

             char ch;

             int i=0,sum=0,n=0;

              while(File)

      {             File.get(ch);

                    a[i]=ch;

                    i++;

                    if((ch==’ ‘) || ch(== ‘.’)||(char==’,’)(ch==’\t’)||(ch==’\n’)

                   {i --; sum=sum +i;

                   i=0; N++;

               }

       }

      cout<<”average word size is “<<(sum/n);

  }

Assume a text file “coordinate.txt” is already created. Using this file create a C++ function to count the number of words having first character capital.

   int countword()

  {           ifstream Fin(“BOOK.txt”);

               char ch[25];

               int count=0;

               while(!Fin.eof())

                        {Fin>>ch;

                      if (isupper(ch[0]))

                      count++;

                  }

           Fin.close();

          return count;

              }

Function to count number of lines from a text files (a line can have maximum 70 characters or ends at ‘.’)

int countword()

{          ifstream Fin(“BOOK.txt”);

           char ch[70];

           int count=0;

           if (!Fin)

{             cout<<”Error opening file!” ;

               exit(0);

        }

       while(1)

{Fin.getline(ch,70,‘.’);

if    (Fin.eof())

     break;

     count++;

}

     Fin.close();

     return count;

}

A program to display the size of a file in bytes.

#include<iostream.h>

#include<fstream.h>

#include<process.h>

#include<conio.h>

int main()

{

char filename[13];

clrscr();

cout<”Enter Filename:\n”;

cin.getline(filename,13);

ifstream infile(filename);

if(!infile)

{cout>>”sorry ! Can not open “<<filename <<”file\n”;

exit(-1);

}

long no_bytes=0;

char ch;

infile.seekg(0,ios::end);

no_bytes=infile.tellg();

cout<<”File Size is”<<no_bytes<<”bytes\n”;

return 0;

}

Text files in output mode:

C++ program, which initializes a string variable to the content “There is an island of opportunity in the middle of every difficulty.” and output the string one character at a time to the disk file “OUT.TXT”.

#include<fstream.h>

int main()

{ ofstream fout(“OUT.TXT”);

char *str = ”There is an island of opportunity in the middle of every difficulty.” ;

int i=0;

if(!fout)

{

   cout<<”File cannot be opened “;

return 0;

}

while (str[i]!=’\0’)

{fout<<str[i];

i++;

}f

out.close();

}

Exercise: (2 Marks Questions)

1. te a function in a C++ to count the number of uppercase alphabets present in a text file “BOOK.txt”

2. Write a function in a C++ to count the number of alphabets present in a text file “BOOK.txt”

3. Write a function in a C++ to count the number of digits present in a text file “BOOK.txt”

4. Write a function in a C++ to count the number of white spaces present in a text file “BOOK.txt”

5. Write a function in a C++ to count the number of vowels present in a text file “BOOK.txt”

6. Write a function in a C++ to count the average word size in a text file “BOOK.txt”

7. Write a function in C++ to print the count of the word “the” as an independent word in a text file

STORY.TXT.

For example, if the content of the file STORY.TXT is

There was a monkey in the zoo.

The monkey was very naughty.

Then the output of the program should be 2.

8. Assume a text file “Test.txt” is already created. Using this file, write a function to create three

files “LOWER.TXT” which contains all the lowercase vowels and “UPPER.TXT” which contains

all the uppercase vowels and “DIGIT.TXT” which contains all digits.

9. Create a function FileLowerShow() in c++ which take file name(text files)as a argument and display its all data into lower case

10. Write a function in C++ to count the number of lines present in a text file “Story.txt”.

HOTS FILE HANDLING

1. Write a function in a C++ to count the number of consonants present in a text file “Try.txt”

2. Write a function in a C++ to count the number of uppercase vowels present in a text file “Novel.txt”

3. Write a function in a C++ to display the sum of digits present in a text file “Fees.txt”.

4. Write a function in a C++ to display the product of digits present in a text file “Number.txt”.

5. Write a function in a C++ to find the largest digit present in a text file “Marks.txt”

3 Marks Questions

General program structure used for operating a Binary File

Program to read and write a structure using read() and write() using binary file.

struct student

{

    char name[15];

    float percent;

};

    void main()

{

    clrscr();

    student s;

    strcpy(s.name,”rasha”);

    s.percent=89.50;

    ofstream fout;

    fout.open(“saving”, ios::out | ios:: binary);

   if(!fout)

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