Arrays of Structs

1. Arrays of Structs

2. Introduction • A common way to hold data is in an array. • A common way to represent data is with a struct. • Many times you will need to put them both together. • Accessing the array of structs is fairly easy, once you get used to it.

3. Example struct Record { string ID; int Value; string Description; };

4. Record MyArray[10];//declares an array of //10 structs of type Record //set up a blank record for initialization Record Blank; Blank.ID = “”; Blank.Value = 0; Blank.Description = “”; //initialize the array to blank for ( int i =0; i < 10; i++ ) MyArray[i] = Blank;

5. //read in a some values that need to be //stored in >> ID >> Value >> Description; //Store them in an array location MyArray[0].ID = ID; MyArray[0].Value = Value; MyArray[0].Description = Description; //You can fill the entire array this way, like in a loop or //something. //Now you can do things like sort or print //them

6. Sorting void Sort ( Record Array[], int size ) { Record TempRecord; int smallest; for ( int i=0; i < size-1; i++ ) { smallest = i; for ( int j = i+1; j < size; j++ )

7. { if ( Array[smallest].ID > Array[j].ID ) smallest = j; } TempRecord = Array[i]; Array[i] = Array[smallest]; Array[smallest] = TempRecord; } }

8. Printing void Print(Record Array[], int size, ofstream& out) { for ( int i=0; i<size; i++ ) out << setw(15) << Array[i].ID <<setw(15) << Array[i].Value << setw(40) << Array[i].Description << endl; }

9. Structs with Arrays • There are also times when a Struct may have an array inside. • This is also not too bad, once you get used to it. • Let’s take a look at an example:

10. Example struct Student { string name; int grades[10]; };

11. Now we can use the struct • Student dave; • dave.name = “Fred”; • for ( int i = 0; i < 10; i++ ) • dave.grades[i] = 0; • Or • dave.grades[5] = 10;