How to retrieve string of keys out of nested map at same time

Question

I have a nested std::map of student info that looks like this:

{
 "class":[
         "student":{
             "name":"Collin",
             "average":"100",
             "family":{
             "%type":"nuclear",
             "%parent":"divorced",
             "#text":"3"
             } //family
          } //student
          "student":{
             "name":"Jamie",
             "average":"95",
             "family":{
             "%type":"nuclear",
             "%parent":"single",
             "#text":"2"
             } //family
          } //student
   ] //class
}//overall Map

where(above) - {} represents a Map
             - [] represents a List

I'm trying to retrieve the info like this:

std::string student0Name = l_mapClassOfStudents[std::string("class")][std::string("student")][0][std::string("name")]; //see error message about operator for [ before student

However, I'm getting no operator [] matches these operands. This is at the [ right before student in the line above.

I saw this list inside map, but it doesn't say how to get items out.

EDIT: This is what I wound up with, using our internal definitions of String, VariantMap, VariantList, Variant (hopefully they map closely to standard Variant, VariantMap, VariantList, but I'm not sure if it does or not):

//Collin
VariantMap familyInfo0;
familyInfo0[String("%type")] = Variant("nuclear");
familyInfo0[String("%parent")] = Variant("single");
familyInfo0[String("#text")] = Variant("3");
VariantMap studentInfo0;
studentInfo0[String("name")] = Variant("Collin");
studentInfo0[String("average")] = Variant("100");
studentInfo0[String("family")] = familyInfo0;

VariantMap classInfo;
VariantList students;
VariantMap studentMap0;
studentMap0[String("student")] = studentInfo0;
VariantMap studentMap1;
studentMap1[String("student")] = studentInfo1;
students.push_back(studentMap0);
students.push_back(studentMap1);
classInfo[String("class")] = students;
Variant student0Name = classInfo[String("class")].cast<VariantList>()[0].cast<VariantMap>()[String("name")];

Answer 1

If the students are in a list, use front() to retrieve the first element:

std::string student0Name = l_mapClassOfStudents[std::string("class")].front()[std::string("name")];

I think a better structure would be something like

typedef map<string,string> Student;
typedef list<Student> Class;
typedef list<Class> School;

Lists are usually used for iterating through. Alternatively you could use vector instead of list to access them by number:

typedef map<string,string> Student;
typedef vector<Student> Class;
typedef vector<Class> School;
cout << thisSchool[3][2]["name"]; // name of the 3rd student in the 4th class, if thisSchool is of type School (and enough classes and students exist)