instance of 'std::out_of_range' problem

[wooldoor11]

this is the message I get when I compile my program:
terminate called after throwing an instance of 'std::out_of_range'
what(): basic_string::substr
I still haven't been able to put my finger on where the problem is. Here is my code:

#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>

using namespace std;

struct album
{
string albumN,year,songL[30],song[30];
int c;
};

void sSort(string ar[], string arL[], int elems)
{
int swaps = 1,j;
while(swaps)
{
swaps = 0;

for(j = 0; j < elems-1; j++)
{
if(arL[j].compare(arL[j+1]) == 1)
{
swap(arL[j],arL[j+1]);
swap(ar[j],ar[j+1]);
swaps = 1;
}
}
}
}

void sort_albums( struct album beatles[], int c)
{
int swaps = 1,j;
while(swaps)
{
swaps = 0;
for(j = 0; j < c-1; j++)
{
if(beatles[j].albumN.compare(beatles[j+1].albumN) == 1)
{
swap(beatles[j],beatles[j+1]);
swaps = 1;
}
}
}
}


int main ()
{
const int size = 5;
string line,ar[200];
struct album beatles[size];
int len,i = 0,x = 0;

ifstream beatlesData ("beatles.cpp"); //opening the file.

if (beatlesData.is_open()) // if the file is open
{
while (!beatlesData.eof()) // while the end of file is NOT reached
{
for(x = 0; x < size; x++)
{

// get album name
getline(beatlesData,line);
beatles[x].albumN = line;

// get album year
getline(beatlesData,line);
beatles[x].year = line;
beatles[x].c = 0;

// get the first song
getline(beatlesData,line);

// get the rest of the songs
// get album songs
do
{
len = line.length();
beatles[x].song[i] = line;
beatles[x].songL[i] = beatles[x].song[i].substr(4,len);
beatles[x].c++;
getline(beatlesData,line);
i++;
} while(line[0] != '=' && !beatlesData.eof());

//sort songs

sSort(beatles[x].song, beatles[x].songL, i);
// reset the number of songs to 0
i = 0;
}
}

sort_albums(beatles, 5);

for(int y = 0; y < size; y++)
{
cout << beatles[y].albumN << endl;
cout << beatles[y].year << endl;
for(int x = 0; x < beatles[y].c; x++)
{
cout << beatles[y].song[x] << endl;
}
cout << "==============================" << endl;
}
beatlesData.close(); //closing the file
}

else cout << "Unable to open file"; //if the file is not open output
return 0;
}

[JLBorges]

> beatles[x].song[i].substr(4,len);

The exception would be thrown if the string is not long enough; ie. beatles[x].song[i].size() is less than 4.

[wooldoor11]

I increased the size but am still getting the same error. Perhaps my size is still not large enough?

[MikeyBoy]

Why not just check that the string is long enough before looking for the substring?