How to discard extra inputs in a line c++ - c++

Question

I am a novice in C++. I am trying to get input from the user for inserting in a multidimensional vector. The code works fine. But when I give extra inputs in the same line, my program does not disregard it and considers it in the next iteration.
For example when I give input in the following format:
m=3 n=4
1 2 3 4 5
1 3 5 5
1 345 65 567
the output is
1 2 3 4
5 1 3 5
5 1 345 65
But what the output I want is
1 2 3 4
1 3 5 5
1 345 67 567
int main() {
vector<vector<int>> vec;
int m, n, dat;
cout << "Enter dimensions of Vector";
cin >> m >> n;
// takes data n times into a subvector temp and inserts it into the vector vec m
// times
cout << "Enter elements one row at a time";
for(int i = 0; i < m; ++i) {
vector<int> temp;
for(int j = 0; j < n; ++j) {
cin >> dat;
temp.push_back(dat);
}
vec.push_back(temp);
}
for(int k = 0; k < vec.size(); ++k) {
for(int i = 0; i < vec[k].size(); ++i) {
cout << setw(4) << vec[k][i];
}
cout << endl;
}
}

Answer 1

Consider using std::getline to read a complete line. You can then use that to populate a std::istringstream that you then use to extract the exact number of elements you want. Also note:
Why is “using namespace std;” considered bad practice?
Example:
#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
int main() {
std::vector<std::vector<int>> vec;
int m, n, dat;
std::cout << "Enter dimensions of Vector";
std::cin >> m >> n;
std::cin.ignore(); // skip newline
// takes data n times into a subvector temp and inserts it into the vector vec m
// times
std::cout << "Enter elements one row at a time\n";
for(int i = 0; i < m; ++i) {
std::string line;
std::vector<int> temp;
std::cout << " row " << (i + 1) << ": ";
std::getline(std::cin, line);
std::istringstream iss(line);
for(int j = 0; j < n; ++j) {
iss >> dat;
temp.push_back(dat);
}
vec.push_back(temp);
}
for(const auto& row : vec) {
for(int colval : row) {
std::cout << std::setw(4) << colval;
}
std::cout << "\n";
}
}