Not getting all lines from a text file when using getline () in C ++

Question

I was assigned homework to create a txt file containing a random number of lines, each of which has a random number of integers, starting from the minimum value and maximum value. A large number of rands ().

In any case, it was the easy part. The second part of the problem is to read the first file and create a second file containing some statistics, such as: the sum of all integers in the file, their average value, the minimum and maximum values ​​and my main problem: the sum of all integers in each line.

I wrote the following code:

#include <iostream> #include <fstream> #include <string> #include <sstream> #include <cstdlib> #include <cmath> using namespace std; int main() { string newLine; stringstream ss; int newInput = 0, oldInput = 0; int lineSum = 0; int lineCounter = 0; int allSum = 0; int intCounter = 0; double averageOfAll = 0; int minInt = 0; int maxInt = 0; 

.... // generate the first file. There is no problem.

 ifstream readFile; readFile.open("inputFile.txt"); ofstream statFile; statFile.open("stat.txt"); if(readFile.is_open()) { while (getline(readFile, newLine)) { //my problem should be somewhere //around here... ss.str(""); ss << newLine; while(!ss.eof()) { oldInput = newInput; ss >> newInput; cout << newInput << endl; lineSum += newInput; allSum += newInput; intCounter++; minInt = min(oldInput, newInput); maxInt = max(oldInput, newInput); } lineCounter++; statFile << "The sum of all integers in line " << lineCounter << " is: " << lineSum << endl; lineSum = 0; } readFile.close(); averageOfAll = static_cast<double>(allSum)/intCounter; statFile << endl << endl << "The sum of all integers in the whole file: " << allSum; statFile << endl << "The average of value of the whole stream of numbers: " << averageOfAll; statFile << endl << "The minimum integer in the input file: " << minInt; statFile << endl << "The maximum integer in the input file: " << maxInt; statFile << endl << endl << "End of file\n"; } else cout << endl << "ERROR: Unable to open file.\n"; statFile.close(); return 0; } 

When the program starts, it seems that my loops iterate over all the lines in the file. However, they only collect integers from the first line, and the rest remain 0.

I would post screenshots of my speeches, but I don't have enough reputation :( can anyone help?

---

It worked!

inputFile.txt ^

statFile.txt (my conclusion) ^

And, as P0W and James Kanze suggested, this was a flag issue and misuse of my streamstring. I adjusted my code as follows:

 . . . while (getline(readFile, newLine)) { stringstream ss(newLine); while(ss >> newInput) { lineSum += newInput; allSum += newInput; intCounter++; minInt = min(minInt, newInput); maxInt = max(maxInt, newInput); } . . . 

Thanks everyone!

Answer 1

There are a few questions, but the main thing is that you are trying to reuse ss (which should be properly std::istringstream ). This can be done, but it is justifiably hard to get right, since threads have many states that require reinitialization. (In this case, the stream remembers that it saw the end of the file and does nothing until it has been reset.) Your loop should look like this:

 while ( getline( readFile, newLine ) ) { std::istringstream ss( newLine ); // ... } 

And once you get std::istringstream , you don’t want a loop until eof (which may or may not be installed after the last successful input); you want to run the loop until the input completes with an error. (After the input fails, you can check eof : if it is not set, the input failed due to a format error in the line; for example, someone entered "abc" instead of an integer.)

Answer 2

You can try to execute your inner while loop

 ss << newLine; while( ss >> newInput ) { //.... Your logic, // might need little update oldInput = newInput; } ss.clear( ); // clear the flags !