向量 <string> push_back崩溃

Question

My first motivation is to using "vector< set >" like this:

ifstream fin(file)
string line;
vector< set<string> > diag;
set<string> temp_set;
vector<string> temp_vec;
while(getline(fin, line)
{ 
    temp_vec = split(line, " ");
    for(int i = 0;i < temp_vec.size();i ++)
       temp_set.insert(temp_vec[i]);
    diag.push_back(temp_set)
}

but it crashed, then I use "vector" to debug the code. But interesting is that, the program also crashed when I tried to push_back each line of string into the vector. Here is the code that very simple.

ifstream fin(file);
string line;
vector<string> diag;
while(getline(fin, line))
    diag.push_back(line);

The program will suddenly crashed when reading some line. In addition, the file is big about 4G. Could anyone help me? thanks a lot.

Answer 1

With this code here your temp_set just keeps getting bigger and bigger because it does not get emptied between lines:

ifstream fin(file);
string line;
vector< set<string> > diag;
set<string> temp_set;
vector<string> temp_vec;
while(getline(fin, line)
{ 
    temp_vec = split(line, " ");
    for(int i = 0;i < temp_vec.size();i ++)
       temp_set.insert(temp_vec[i]); // when is this set emptied?
    diag.push_back(temp_set);
}

Maybe try this:

ifstream fin(file);
string line;
vector< set<string> > diag;
vector<string> temp_vec;
while(getline(fin, line)
{
    temp_vec = split(line, " ");
    // no need for loop
    // construct a new set each time
    set<string> temp_set(temp_vec.begin(), temp_vec.end());
    diag.push_back(temp_set);
}

If you have C++11 you can be even more efficient like this:

std::ifstream fin(file);
std::string line;
std::vector<std::set<std::string> > diag;
std::vector<std::string> temp_vec;

while(std::getline(fin, line))
{
    temp_vec = split(line, " ");
    diag.emplace_back(temp_vec.begin(), temp_vec.end());
}