Struct must be overloaded in STL.

In STL applications, we often use struct, which requires us to reload operators with specific requirements. For example, in STL, sorting is performed by default using a smaller number. Therefore, when sorting the struct, We need to reload the minor signs.

Example:

# Include <map>
# Include <iostream>
# Include <string>

Using namespace std;

// Student Information
Typedef struct tagStudentInfo
{
Int nID;
String strName;
Bool operator <(const tagStudentInfo & A) const
{
If (nID <A. nID) return true; // compare nID first
If (nID = A. nID) return strName. compare (A. strName) <0; // compare strName
Return false;
}

} StudentInfo, * pstudentInfo;

Int main ()
{
// Map scores with student information
Map <StudentInfo, int> mapStudent;

StudentInfo studentInfo;

StudentInfo. nID = 1;
StudentInfo. strName = "student_one ";
MapStudent. insert (map <StudentInfo, int >:: value_type (studentInfo, 90 ));

StudentInfo. nID = 2;
StudentInfo. strName = "student_two ";
MapStudent. insert (map <StudentInfo, int >:: value_type (studentInfo, 80 ));

StudentInfo. nID = 2;
StudentInfo. strName = "student_three ";
MapStudent. insert (map <StudentInfo, int >:: value_type (studentInfo, 80 ));

Map <StudentInfo, int >:: iterator iter;
For (iter = mapStudent. begin (); iter! = MapStudent. end (); iter ++)
Cout <iter-> first. nID <iter-> first. strName <endl <iter-> second <endl;

Return 0;
}

 

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