Let's say when I am writing program, sometimes I want to see the variable values. But when I try to overload << operator the leetcode system complains by saying that there is an error.
For example this code:
class Solution {
public:
template <typename T>
friend ostream& operator<<(ostream &out, const vector<T> &v);
int maxProfit(vector<int>& prices) {
int n = prices.size();
vector<vector<int>> indices;
for(int i = 0 ; i < n; i++)
indices[i] = vector<int>{prices[i],i};
sort(indices.begin(), indices.end(),
[](const vector<int> &u, const vector<int> &v){
return (u[0] >= v[0]);
});
cout << indices << endl;
return 0;
}
};
template <typename T>
ostream& operator<< (ostream &out, const vector<T> &v) {
out << "]";
int n = v.size();
if(n > 0) {
for(int i = 0 ; i < n-1; i++) out << v[i] << ", ";
out << v[n-1];
}
out << "]";
return out;
}and I am getting this error:
Line 15: Char 14: error: invalid operands to binary expression ('std::ostream' (aka 'basic_ostream<char>') and 'vector<vector<int>>')
cout << indices << endl;
~~~~ ^ ~~~~~~~
/usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/cstddef:130:5: note: candidate function template not viable: no known conversion from 'std::ostream' (aka 'basic_ostream<char>') to 'std::byte' for 1st argument
operator<<(byte __b, _IntegerType __shift) noexceptwhy?
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