Write a program to count the number of characters words and lines in given text c plus plus?

Answer 1

#include<iostream>

#include<fstream>

int main()

{

std::ifstream infile ("example.txt", std::ios::in);

unsigned chars(0);

unsigned words(0);

unsigned lines(0);

std::string delim("\t\n ");

char ch(0);

char last(0);

if (!infile.good())

{

std::cerr << "The filename is invalid." << std::endl;

return -1;

}

while (infile.get(ch))

{

switch (ch)

{

case ('\n'):

++lines;

case (' '):

case ('\t'):

// only count words if the last char was not a word delimiter

if (delim.find(last) == std::string::npos)

++words;

default:

++chars;

}

last = ch;

}

infile.close();

std::cout << "Number of chars:\t" << chars << std::endl;

std::cout << "Number of words:\t" << words << std::endl;

std::cout << "Number of lines:\t" << lines<< std::endl;

}

Answer 2

You shouldn't use a pointer for this unless you can guarantee the string is null-terminated. Use a std::string instead. The following program demonstrates both methods.

#include<iostream>

#include<string>

bool is_whitespace (const char c)

{

switch (c)

{

case (' '):

case ('\n'):

case ('\t'):

return true;

}

return false;

}

size_t count_words_unsafe (char* p)

{

// this version is unsafe as there's no guarantee

// the given pointer points to a null-terminated

// character array, resulting in undefined behaviour

// initialise the return value

size_t count=0;

// check for null pointer

if (p==nullptr)

return count;

// assume the first character is a whitespace

bool whitespace = true;

// iterate through each character

for ( ; *p!='\0'; ++p)

{

// is the current character a whitespace?

if (is_whitespace (*p))

{

// yes -- is the whitespace flag unset?

if (!whitespace)

{

// yes -- we've reached the end of a word

++count;

// set the whitespace flag

whitespace = true;

}

}

else

{

// unset the whitespace flag

whitespace = false;

}

}

// return the result

return count;

}

size_t count_words_safe (const std::string& s)

{

// this version is safe because std::string

// variables know their own length

// initialise the return value

size_t count=0;

// assume the first character is a whitespace

bool whitespace = true;

// iterate through each character

for (auto c : s)

{

// is the current character a whitespace?

if (is_whitespace (c))

{

// yes -- is the whitespace flag unset?

if (!whitespace)

{

// yes -- we've reached the end of a word

++count;

// set the whitespace flag

whitespace = true;

}

}

else

{

// unset the whitespace flag

whitespace = false;

}

}

// return the result

return count;

}

int main ()

{

// declare a C-style string

char* s

{

"\tThis is a paragraph made up of several lines. Words are\n"

"separated by white space characters, which includes single or\n"

"multiple spaces, tabs and newlines. There are 40 words in this\n"

"paragraph. Note that the first character is a whitespace.\n"

};

std::cout << "The paragraph:\n\n" << s << std::endl;

size_t safe_count = count_words_safe (s);

std::cout << "Safe count:\nThe paragraph has " << safe_count << " words.\n" << std::endl;

size_t unsafe_count = count_words_unsafe (s);

std::cout << "Unsafe count:\nThe paragraph has " << unsafe_count << " words.\n" << std::endl;

}