sortId: identifier not found - c++

Question

I'm trying to sort the students by first name, grade, and id.
When I run it, it gives me the error "identifier not found."
and I'm kind of confused because I have the void sortsID in the struct before the main.
This is in my main which includes my myDate.h. I only included some of the code that I thought was important in this question
main.cpp
struct studentData {
int id;
string name;
myDate birthday;
int grade;
void sortID(studentData, int);
void sortGrade(studentData, int);
};
int main() {
studentData myClass[10];
myClass[0].name = "blah blah";
//adding names to class
//random id numbers, bday, grade for each student
for (int i = 0; i < 10; i++) {
int randomId = (rand() % (9999 - 1000 + 1)) + 1000;
int randomGrade = (rand() % (100 - 50 + 1)) + 50;
int randomMonth = rand() % (12 - 1) + 1;
int randomDay = rand() % (31 - 1) + 1;
int randomYear = rand() % (1994 - 1990) + 1990;
myDate randomBday(randomMonth, randomDay, randomYear);
myClass[i].id = randomId;
myClass[i].grade = randomGrade;
myClass[i].birthday = randomBday;
}
studentData *idSort[10];
case 2:
cout << "Sorting by ID" << endl;
sortID(myClass, 10);
cout << "Displaying original list";
cout << "Student Info:\n";
cout << "=================================================\n";
cout << "NAME ID# GRADE BDAY\n";
for (int i = 0; i < 10; i++) {
idSort[i] = &(myClass[i]);
cout << left << setw(18) << idSort[i]->name << " ";
cout << left << setw(12) << idSort[i]->id << " ";
cout << setw(11) << setprecision(4) << idSort[i]->grade << " ";
idSort[i]->birthday.display();
cout << " " << endl;
}
break;
system("PAUSE"); };
void sortID(studentData s[], int n) {
studentData temp; // Local variable used to swap records
for (int i = 0; i<n; i++)
{
for (int i = 0; i<n; i++)
{
// If s[i].student_number is greater than s[i+1].student_number,
swap the records
if (s[i].id > s[i + 1].id)
{
temp = s[i];
s[i] = s[i + 1];
s[i + 1] = temp;
}
}
}
}
void sortGrade(studentData s[], int n) {
studentData temp; // Local variable used to swap records
for (int i = 0; i<n; i++)
{
for (int i = 0; i<n; i++)
{
// If s[i].student_number is greater than s[i+1].student_number, swap the records
if (s[i].grade > s[i + 1].grade)
{
temp = s[i];
s[i] = s[i + 1];
s[i + 1] = temp;
}
}
}
}
void sort_on_name(studentData s[], int n) {
studentData temp; // Local variable used to swap records
for (int i = 0; i<n; i++)
{
for (int i = 0; i<n; i++)
{
// If s[i].name is later in alphabet than s[i+1].name, swap the two records
if (strcmp(s[i].name, s[i + 1].name) > 0)
{
temp = s[i];
s[i] = s[i + 1];
s[i + 1] = temp;
}
}
}
}
`

Answer 1

You declared function sortID as a non-static member function of class studentData
struct studentData {
int id;
string name;
myDate birthday;
int grade;
void sortID(studentData, int);
void sortGrade(studentData, int);
};
But you call it as a non-member function
sortID(myClass, 10);
Of course the compiler does not know how this name is declared because you declared name
studentData::sortID
Moreover the function defined after main with name sortID differs from the member function because its first parameter has type studentData s[] while the early declared function has the first parameter of type studentData
void sortID(studentData s[], int n) {
studentData temp; // Local variable used to swap records
for (int i = 0; i<n; i++)
{
for (int i = 0; i<n; i++)
{
// If s[i].student_number is greater than s[i+1].student_number,
swap the records
if (s[i].id > s[i + 1].id)
{
temp = s[i];
s[i] = s[i + 1];
s[i + 1] = temp;
}
}
}
}

Answer 2

Thank you guys for all your help!
I just used the #include < algorithmn >
So I just added this between the studentData and main()
struct compare_student_by_id {
bool operator() (const studentData & lhs, const studentData & rhs) {
return lhs.id < rhs.id;
}};
and included
std::sort(myClass, myClass + 10, compare_student_by_id());
in the main.