Write Album's PrintSongsShorterThan() to print all the songs from the album shorter than the value of the parameter songDuration. Use Song's PrintSong() to print the songs.

Here is the function PrintSongsShorterThan() which prints all the songs from the album shorter than the value of the parameter songDuration.

void Album::PrintSongsShorterThan(int songDuration) const {   //function that takes the songDuration as parameter

unsigned int i;  

Song currSong;    //object of Song

cout << "Songs shorter than " << songDuration << " seconds:" << endl;  

for(int i=0; i<albumSongs.size(); i++){    

currSong = albumSongs.at(i);    

if(currSong.GetDuration()<songDuration){    //checks if the song duration of the song from album is less than the value of songDuration

currSong.PrintSong();     } } }  //calls PrintSong method to print all the songs with less than the songDuration

Explanation:  

I will explain the working of the for loop in the above function.

The loop has a variable i that is initialized to 0. The loop continues to execute until the value of i exceeds the albumSongs vector size. The albumSongs is a Song type vector and vector works just like a dynamic array to store sequences.

At each iteration the for loop checks if the value of i is less than the size of albumSongs. If it is true then the statement inside the loop body execute. The at() is a vector function that is used to return a reference to the element at i-th position in the albumSongs.  

So the album song at the i-th index of albumSongs is assigned to the currSong. This currSong works as an instance. Next the if condition checks if that album song's duration is less than the specified value of songDuration. Here the method GetDuration() is used to return the value of duration of the song. If this condition evaluates to true then the printSong method is called using currSong object. The printSong() method has a statement cout << name << " - " << duration << endl; which prints/displays the name of the song with its duration.

If you see the main() function statement:

musicAlbum.PrintSongsShorterThan(210);  

The musicAlbum is the Album object to access the PrintSongsShorterThan(210) The value passed to this method is 210 which means this is the value of the songDuration.

As we know that the parameter of PrintSongsShorterThan method is songDuration. So the duration of each song in albumSongs vector is checked by this function and if the song duration is less than 210 then the name of the song along with its duration is displayed on the output screen.

For example if the album name is Anonymous and the songs name along with their duration are:

ABC 400  

XYZ 123  

CDE 300  

GHI 200  

KLM 100  

Then the above program displays the following output when the user types "quit" after entering the above information.

Anonymous                                                              

Songs shorter than 210 seconds:                                                                         XYZ - 123                                                                                                              

GHI - 200                                                                                                              

KLM - 100  

Notice that the song name ABC and CDE are not displayed because they exceed the songDuration i.e. 210.