CBSE Class 12 Computer Science Chapter 6: Data File Handling NCERT Solutions

To count the words in a text file, we can read the file word by word and increment a counter for each word read. The extraction operator (>>) in C++ reads whitespace-separated strings, which naturally separates words.

Here is the C++ function:

#include <iostream>

#include <fstream>

#include <string>

void word_count() {

std::ifstream inputFile("opinion.txt");

std::string word;

int count = 0;

if (inputFile.is_open()) {

// Read words until the end of the file is reached

while (inputFile >> word) {

count++; // Increment count for each word successfully read } inputFile.close();

std::cout << "Total number of words present in the text file are: " << count << std::endl;

} else {

std::cout << "Error opening file." << std::endl; } }

Explanation:

1. Include necessary headers: <iostream> for input/output and <fstream> for file operations.
2. Declare an ifstream object named inputFile and associate it with the file "opinion.txt".
3. Initialize an integer variable count to 0 to store the word count.
4. Check if the file was opened successfully using inputFile.is_open().
5. Use a while loop with the condition inputFile >> word. This attempts to read the next word from the file into the word string. The loop continues as long as words can be successfully extracted.
6. Inside the loop, increment the count for each word read.
7. After the loop finishes (end of file reached), close the file using inputFile.close().
8. Finally, display the total word count.

This function will read the file word by word, check the length of each word, and count only those that have exactly three letters. The strlen() function is used to determine the length of each word.

Here is the C++ function:

#include <iostream>

#include <fstream>

#include <string>

#include <cstring> // For strlen

void countThreeLetterWords() {

std::ifstream inputFile("VOWEL.TXT");

char word[80]; // Buffer to store each word

int count = 0;

if (inputFile.is_open()) {

// Read words until the end of the file

while (inputFile >> word) {

// Check if the length of the word is exactly 3

if (strlen(word) == 3) {

count++; // Increment count if it's a three-letter word } }

inputFile.close();

std::cout << "Number of three-letter words = " << count << std::endl;

} else {

std::cout << "Error opening file." << std::endl; } }

Explanation:

1. Include necessary headers: <iostream>, <fstream>, <string>, and <cstring> for strlen.
2. Declare an ifstream object inputFile for "VOWEL.TXT".
3. Use a character array word to store each word read from the file.
4. Initialize count to 0.
5. Open the file and check if it was successful.
6. Use a while loop (inputFile >> word) to read words.
7. Inside the loop, use strlen(word) to get the length of the current word.
8. If the length is exactly 3, increment the count.
9. Close the file and display the final count.

This function reads the file character by character and checks if each character is either 'A'/'a' or 'E'/'e'. It maintains separate counters for both.

Here is the C++ function:

#include <iostream>

#include <fstream>

void AECount() {

std::fstream file("NOTES.TXT", std::ios::in);

char character;

int countA = 0;

int countE = 0;

if (file.is_open()) {

// Read characters one by one until end of file

while (file.get(character)) {

// Check for 'A' or 'a'

if (character == 'A' || character == 'a') {

countA++; } // Check for 'E' or 'e'

else if (character == 'E' || character == 'e') {

countE++; } }

file.close();

std::cout << "A: " << countA << " E: " << countE << std::endl;

} else {

std::cout << "Error opening file." << std::endl; } }

Explanation:

1. Include necessary headers: <iostream> and <fstream>.
2. Declare an fstream object named file and open "NOTES.TXT" in input mode (std::ios::in).
3. Initialize two integer variables, countA and countE, to 0.
4. Check if the file was opened successfully.
5. Use a while loop with file.get(character) to read characters one by one. The loop continues as long as a character is successfully read.
6. Inside the loop, use an if statement to check if the character is 'A' or 'a'. If it is, increment countA.
7. Use an else if statement to check if the character is 'E' or 'e'. If it is, increment countE.
8. After reading the entire file, close it using file.close().
9. Display the final counts for 'A' and 'E'.