read string and numbers to vector c++ - c++

Question

What can I do when my file s2.txt looks like
ID 1 (string)
22 30 30 4 2 4 5 7 5 3 ......................................(a few lines
of numbers)
ID 2
30 4 2 1 2 ................................. (other lines of numbers)
I want save numbers to vector but it doesn't work:
void readFromFile (){
ifstream file("s2.txt");
if( file.good() == true )
cout << "open" << endl;
else
cout << "denied" << endl;
int m=0;
while(!file.eof()) {
string ID;
int qual;
vector <int> quality;
getline(file,ID);
while (file>>qual) {
quality.push_back(qual);
cout<<quality[m]<<endl;
m++;
}
}
file.close();
}
}
main () {
readFromFile();
}
When I click "Run" only one string of numbers is save to a vector (for ID1).
PS. Reading ID is not important.

Answer 1

You should read each line to a string. Then check for "ID" string. If "ID" string is found at position 0 of a line then read that line as a ID line, if not, read that line as a line of integer numbers.

Answer 2

As suggested in the answer of Linh Dao, I made a respective sample code:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
void readFromFile(std::istream &in)
{
if (!in.good()) {
std::cerr << "ERROR!" << std::endl;
}
std::string buffer;
std::vector<int> quality;
while (std::getline(in, buffer)) {
if (buffer.size() >= 2 && buffer.compare(0, 2, "ID") == 0) {
std::cout << buffer << std::endl;
quality.clear(); // reset quality vector
} else {
// read numbers
std::istringstream in(buffer); int qual;
while (in >> qual) {
quality.push_back(qual);
std::cout << quality.back() << std::endl;
}
}
}
}
int main(void)
{
#if 0 // in OP
{ std::ifstream fIn("s2.txt");
readFromFile(fIn);
} // fIn goes out of scope -> file is closed
#else // instead
readFromFile(std::cin);
#endif // 0
return 0;
}
Input:
ID 1 (string)
22 30 30 4 2 4 5 7 5 3
22 30 30 4 2 4 5 7 5 3
ID 2
30 4 2 1 2
Output:
ID 1 (string)
22
30
30
4
2
4
5
7
5
3
22
30
30
4
2
4
5
7
5
3
ID 2
30
4
2
1
2
Life demo on ideone.
Note:
The input stream is read line by line (into std::string buffer).
The further processing depends on whether the input buffer contents starts with ID.
If not, the buffer is used with std::istringstream to extract int numbers.
If I understood the comment right, the questioner intended to output the whole collected quality vector in each iteration. Hence, I modified the first sample and added an output operator<<() for std::vector<int>:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
// a stream operator for vector<int> ouput
std::ostream& operator<<(std::ostream &out, const std::vector<int> &values)
{
const char *sep = "";
for (int value : values) {
out << sep << value; sep = " ";
}
return out;
}
void readFromFile(std::istream &in)
{
if (!in.good()) {
std::cerr << "ERROR!" << std::endl;
}
std::string buffer;
std::vector<int> quality;
while (std::getline(in, buffer)) {
if (buffer.size() >= 2 && buffer.compare(0, 2, "ID") == 0) {
std::cout << buffer << std::endl;
quality.clear(); // reset quality vector
} else {
// read numbers
std::istringstream in(buffer); int qual;
while (in >> qual) {
quality.push_back(qual);
std::cout << quality << std::endl;
}
}
}
}
int main(void)
{
#if 0 // in OP
{ std::ifstream fIn("s2.txt");
readFromFile(fIn);
} // fIn goes out of scope -> file is closed
#else // instead
readFromFile(std::cin);
#endif // 0
return 0;
}
Input: the same like above
Output:
ID 1 (string)
22
22 30
22 30 30
22 30 30 4
22 30 30 4 2
22 30 30 4 2 4
22 30 30 4 2 4 5
22 30 30 4 2 4 5 7
22 30 30 4 2 4 5 7 5
22 30 30 4 2 4 5 7 5 3
22 30 30 4 2 4 5 7 5 3 22
22 30 30 4 2 4 5 7 5 3 22 30
22 30 30 4 2 4 5 7 5 3 22 30 30
22 30 30 4 2 4 5 7 5 3 22 30 30 4
22 30 30 4 2 4 5 7 5 3 22 30 30 4 2
22 30 30 4 2 4 5 7 5 3 22 30 30 4 2 4
22 30 30 4 2 4 5 7 5 3 22 30 30 4 2 4 5
22 30 30 4 2 4 5 7 5 3 22 30 30 4 2 4 5 7
22 30 30 4 2 4 5 7 5 3 22 30 30 4 2 4 5 7 5
22 30 30 4 2 4 5 7 5 3 22 30 30 4 2 4 5 7 5 3
ID 2
30
30 4
30 4 2
30 4 2 1
30 4 2 1 2
Life demo on ideone.