not sure what i'm doing wrong but this is my code
int main (){
int marks [100];
int i=0;
ifstream inputfile;
ofstream outputfile;
inputfile.open("data.txt");
if(!inputfile.is_open())
{
cout<< "File did not open"<< endl;
return 0;
}
cout<<"Marks in File:"<<endl;
while (marks [i] != -1)
{
inputfile>>marks[i];
cout << marks[i] <<endl;
i++;
}
return 0;
}
the output is messed up and returns stuff that was never in the data file to begin with
Here is the minimal code for reading data from a file and write it to console. Description is added as comments
#include <fstream>
#include <sstream>
#include <string>
#include <iostream>
using namespace std;
int main()
{
ifstream configrecord("D:\\Temp\\temp.txt"); // opening the file named temp for reading.
if(configrecord.good()) // check whether the file is opened properly.
{
string line;
while (getline(configrecord, line)) // reading a line from file to std::string
{
cout << line; // printing the line, if you want it to store in an array, you can use the std::string::data() api to get the character pointer.
}
configrecord.close(); // closing the file after reading completed
}
}
If we translate your code to English, we get:
Notice a big problem: We're checking if the value is -1 before we actually read it. We need to reverse the order of steps 1 and 2 so that we get:
We can do this by using true as our loop condition and then using an if statement to check if the inputted value is -1 later in the loop, using break to break the loop if it is.
#include <fstream>
#include <iostream>
//using namespace std; is considered bad practice
int main()
{
std::ifstream inFile("input.txt");
int marks[100];
//check if file is open stuff...
for(int i = 0; true; i++)
{
inFile >> marks[i];
if(marks[i] == -1) break;
std::cout << marks[i] << '\n'; //endl flushes the buffer, unnecessary here.
}
}
Of Note: it is good practice that if you use an if statement, you also include an else statement. Also, your while loop is confusing, because it stops if it encounters negative one, so I am assuming you know that integer -1 is not in the file.
int n = -1;
if(!inputfile.is_open())
{
cout<< "File did not open"<< endl;
}
else
{
cout<<"Marks in File:"<< endl;
while(!inputfile.eof()){ // .eof is bad practice, but for this instance it works.
File >> marks[n];
n++; // Essentially the size of the array (Number of values), keeping track of how many values there are will assist you in the output process.
}
}
When you are done reading the file, you should close it and then use the data in the array.
inputfile.close();
Lastly, in order to output an array of data, you must use a for loop or some type of iterator to access the values stored in the array.
for(int i=0; i < n ; i++) // Output array. Where array size is less than n.
{
cout << marks[i] << " "; // " " inputs a space in between each word.
}
