Question

C++ question.

I want to write all output to the file "output.txt", but it will write just first character. Can you fix it?

#include

#include

#include

#include

#include

using namespace std;

using std::cin;

using std::cout;

using std::string;

// remove dashes convert letters to upper case

string normalize(const string &isbn) {

string ch;

for (char i : isbn) {

if (i == '-') {

continue; // if "-" then skip it

}

  

if (isalpha(i)) {

i = toupper(i); // Check uppercase

}

ch += i;

}

return ch;

}

// return the number of digits in to the string

size_t numDigits(string &str) {

size_t numDigits = 0;

for (char ch : str) {

if (isdigit(ch)) {

++numDigits;

}

}

return numDigits;

}

enum ValidationCode {

Ok, // validation passed

NumDigits, // wrong number of digits

ExtraChars,// extra characters in isbn

Done

};

enum ValidationCode validate(string &isbn) {

int Done = 4;

string normal = normalize(isbn);

size_t count = numDigits(normal);

if (normal.size() == Done)

exit(0);

if (count != 10) {

return NumDigits;

}

  

if (normal.size() == 10 || normal.size() == 11 && normal[10] == 'X') {

return Ok;

}

return ExtraChars;

}

int main() {

// open a file

ofstream file("output.txt");

//The following code is taken from (https://en.cppreference.com/w/cpp/io/basic_ios/fail)

// check if the file can open

if(!file) // operator! is used here

{

std::cout << "File opening failed\n";

return EXIT_FAILURE;

} //end of borrowed code

  

// read a file

//The following code is referenced from (https://stackoverflow.com/questions/7868936/read-file-line-by-line-using-ifstream-in-c)

std::ifstream ifs("test_data.txt");

// check if the file can read

if (ifs.fail())

{

std::cerr << "test_data.txt could not read" << std::endl;

return -1;

} //end of referenced code

std::string str;

while (ifs >> str){

switch (validate(str)) {

case Ok:

cout << str << " is a valid isbn\n";

file << str << " is a valid isbn\n";

break;

case NumDigits:

cout << str << " doesn't have 10 digits\n";

file << str << " doesn't have 10 digits\n";

break;

case ExtraChars:

cout << str << " has extra characters\n";

file << str << " has extra characters\n";

break;

default:

cout << "ERROR: validate(" << str << ") return an unknown status\n";

file << "ERROR: validate(" << str << ") return an unknown status\n";

break;

}

}

ifs.close();

file.close();

}

test_data.txt

1-214-02031-3
0-070-21604-5
2-14-241242-4
2-120-12311-x
0-534-95207-x
2-034-00312-2
1-013-10201-2
2-142-1223
3-001-0000a-4
done

Answer 1

/* the problem was buffer got full to clear it we have to use flush method */

/* Run code it's working now*/

#include<iostream>

#include<fstream>

using namespace std;

// remove dashes convert letters to upper case

string normalize(const string &isbn) {

string ch;

for (char i : isbn) {

if (i == '-') {

continue; // if "-" then skip it

}

  

if (isalpha(i)) {

i = toupper(i); // Check uppercase

}

ch += i;

}

return ch;

}

// return the number of digits in to the string

size_t numDigits(string &str) {

size_t numDigits = 0;

for (char ch : str) {

if (isdigit(ch)) {

++numDigits;

}

}

return numDigits;

}

enum ValidationCode {

Ok, // validation passed

NumDigits, // wrong number of digits

ExtraChars,// extra characters in isbn

Done

};

enum ValidationCode validate(string &isbn) {

int Done = 4;

string normal = normalize(isbn);

size_t count = numDigits(normal);

if (normal.size() == Done)

exit(0);

if (count != 10) {

return NumDigits;

}

  

if (normal.size() == 10 || normal.size() == 11 && normal[10] == 'X') {

return Ok;

}

return ExtraChars;

}

int main() {
  
   // open a file
  
   ofstream file("output.txt");

  
   if(!file) // operator! is used here
  
   {
  
   std::cout << "File opening failed\n";
  
   return EXIT_FAILURE;
  
   } //end of borrowed code
      
  
   ifstream ifs("test_data.txt");
  
   // check if the file can read
  
   if (ifs.fail())
  
   {
  
   std::cerr << "test_data.txt could not read" << std::endl;
  
   return -1;
  
   } //end of referenced code
  
   string str;

  
   while (ifs >> str){

   switch (validate(str)) {
  
       case Ok:
               cout << str << " is a valid isbn\n";
               file << str << " is a valid isbn\n";
           break;  
       case NumDigits:
      
               cout << str << " doesn't have 10 digits\n";
               file << str << " doesn't have 10 digits\n";
      
           break;
      
       case ExtraChars:
      
           cout << str << " has extra characters\n";
          
           file << str << " has extra characters\n";
          
           break;
  
       default:
  
           cout << "ERROR: validate(" << str << ") return an unknown status\n";
  
           file << "ERROR: validate(" << str << ") return an unknown status\n";
  
           break;
  
       }
       file.flush(); // to clear buffer
   }
  
   ifs.close();
  
   file.close();

}  

/* PLEASE UPVOTE */

/* OUTPUT */