CPP

c++ how to read from a file

#include <fstream>
#include <iostream>

using namespace std;

int main() {
    /* You create a stream using the file in a 
     * similar way to how we use other streams.
     */
    ifstream in;
    // Open the file
    in.open("names.txt");
    if(in.fail())
        cout << "File didn't open"<<endl;

    int count = 0;
    string line;
    while (true) {
        /* Get line will work as long as there is
         * a line left. Once there are no lines 
         * remaining it will fail. 
		 */
        getline(in, line);  
        if (in.fail()) break;
        
        /* Process the line here. In this case you are
         * just counting the lines.
         */
        count ++;
    }
    
    cout << "This file has " << count << " lines." << endl;
    return 0;
}

How to read files in C++

#include <fstream> 

/*
ofstream 	Creates and writes to files
ifstream 	Reads from files
fstream 	A combination of ofstream and ifstream: creates, reads, and writes to files
*/

int main() {
  // Create and open a text file
  ofstream MyFile("filename.txt");

  // Write to the file
  MyFile << "Files can be tricky, but it is fun enough!";

  // Close the file
  MyFile.close();
} 

c++ read file

#include <stdio.h>

#define n 1024 // n bytes

int main(void) {
	FILE *fp;
    size_t numread;
    if ((fp = fopen("yourfile.xy", "rb") != NULL) {
    	char buffer[n];
        numread = fread(buffer, sizeof(*buffer), n, fp);
      	printf("Read %d Bytes: %s", numread, buffer);
      
      	fclose(fp);
      	return 0;
    }
        
    return -1;
}

cpp read from file

freopen("filename.extension", "r", stdin);