Question

i am trying to sort vector of struct’s elements,but i can’t construct vector itself here is code

#include <string>
#include <vector>
#include <algorithm>
using namespace std;

struct student_t{
      string name;
  int age,score;
}   ;

bool compare(student_t const &lhs,student_t const &rhs){
    if (lhs.name<rhs.name)
         return true;
    else if (rhs.name<lhs.name)
        return false;

    else
        if (lhs.age<rhs.age)
            return true;
        else if (rhs.age<lhs.age)
             return false;
    return lhs.score<rhs.score;

}
int main(){

               struct student_t st[10];







 return 0;
}

when i declared vector<student_t>st i can’t access element of struct,please give me hint how to do it

Answer 1

std::vector<student_t> st;
for(unsigned i = 0; i < 10; ++i) st.push_back(student_t());
std::sort(st.begin(), st.end(), &compare);

You could also use this vector constructor instead of lines 1-2:

std::vector<student_t> st (10 /*, student_t() */);

Edit:

If you want to enter 10 students with the keyboard you can write a function that constructs a student:

struct student_t &enter_student()
{
     student_t s;
     std::cout << "Enter name" << std::endl;
     std::cin >> s.name;
     std::cout << "Enter age" << std::endl;
     std::cin >> s.age;
     std::cout << "Enter score" << std::endl;
     std::cin >> s.score;
     return s;
}
std::vector<student_t> st;
for(unsigned i = 0; i < 10; ++i) st.push_back(enter_student());