Count words in each line of text file in c++ - c++

Question

I open a txt file using argc, argv, and getline. I did that properly, but now I have to get the number of words per line (the number of lines is not known before) and I must output them in reverse. Meaning from the bottom line to the top line. Any help is appreciated. This code outputs the number of words in the file:
#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
int main(int argc, char *argv[])
{
if(argc < 1){
cerr << "Usage: " << argv[0] << "filename.txt" << endl;
}
ifstream ifile(argv[1]);
if(ifile.fail()){
cerr << "Could not open file." << endl;
return 1;
}
int n;
ifile >> n;
cout << n;
int numberOfWords = 0;
string line;
for(int i = 0; i <= n; i++){
getline(ifile, line);
cout << line << endl;
}
size_t i;
if (isalpha(line[0])) {
numberOfWords++;
}
for (i = 1; i < line.length(); i++) {
if ((isalpha(line[i])) && (!isalpha(line[i-1]))) {
numberOfWords++;
}
}
cout<<"The number of words in the line is : "<<numberOfWords<<endl;
return 0;
}

Answer 1

To find the number of words per line you would use std::getline() to iterate over each line and use std::stringstream to extract each chunk of whitespace-separated input. Then you would iterate over each chunk of input and check to see if each character is alphabetic:
int numberOfWords = 0;
for (std::string line, word; std::getline(ifile, line); )
{
std::istringstream iss(line);
while (iss >> word)
{
bool alpha = true;
for (char c : word)
if (!std::isalpha(c)) alpha = false;
if (alpha) ++numberOfWords;
}
std::cout << "Number of words on this line: " << numberOfWords << std::endl;
numberOfWords = 0;
}