int main() {
int yearsToLoop;
cin >> yearsToLoop;
annual_stats* ptr = new annual_stats [yearsToLoop];
for (int i = 0; i < yearsToLoop; i++)
{
int annualYear;
cin >> annualYear;
ptr[i].year = annualYear;
for (int j = 0; j < NO_TEAMS; j++)
{
string team_name;
getline(cin, team_name, '\t');
strcpy(ptr[i].teams[j].team_name, team_name.c_str());
int games;
cin >> games;
ptr[i].teams[j].games = games;
float pts_per_game;
cin >> pts_per_game;
ptr[i].teams[j].pts_per_game = pts_per_game;
int total_points;
cin >> total_points;
ptr[i].teams[j].total_points = total_points;
int scrimmage_plays;
cin >> scrimmage_plays;
ptr[i].teams[j].scrimmage_plays = scrimmage_plays;
float yds_per_game;
cin >> yds_per_game;
ptr[i].teams[j].yds_per_game = yds_per_game;
float yds_per_play;
cin >> yds_per_play;
ptr[i].teams[j].yds_per_play = yds_per_play;
float first_per_game;
cin >> first_per_game;
ptr[i].teams[j].first_per_game = first_per_game;
int third_md;
cin >> third_md;
ptr[i].teams[j].third_md = third_md;
int third_att;
cin >> third_att;
ptr[i].teams[j].third_att = third_att;
int third_pct;
cin >> third_pct;
ptr[i].teams[j].third_pct = third_pct;
int fourth_md;
cin >> fourth_md;
ptr[i].teams[j].fourth_md = fourth_md;
int fourth_att;
cin >> fourth_att;
ptr[i].teams[j].fourth_att = fourth_att;
int fourth_pct;
cin >> fourth_pct;
ptr[i].teams[j].fourth_pct = fourth_pct;
int penalties;
cin >> penalties;
ptr[i].teams[j].penalties = penalties;
int pen_yds;
cin >> pen_yds;
ptr[i].teams[j].pen_yds = pen_yds;
string top_per_game;
cin >> top_per_game;
strcpy(ptr[i].teams[j].top_per_game, top_per_game.c_str());
int fum;
cin >> fum;
ptr[i].teams[j].fum = fum;
int lost;
cin >> lost;
ptr[i].teams[j].lost = lost;
int to;
cin >> to;
ptr[i].teams[j].to = to;
}
}
int numberOfC;
cin >> numberOfC;
for (int i = 0; i < numberOfC; i++)
{
string command;
cin >> command;
if(command == "qsort") {
string command2;
cin >> command2;
int num = atoi(command2.c_str());
if (num >= 2010)
{
string year;
year = command2;
string field;
cin >> field;
string order;
cin >> order;
qSortYearFieldOrder(year, field, order, ptr, yearsToLoop);
}
}
So right here in (part of) the main I get all the inputs and then call a function using some of the inputs. I am currently getting errors with the qSortYearFieldOrder(year, field, order, ptr, yearsToLoop).
void qSortYearFieldOrder(string year, string field, string order, annual_stats* ptr, int amountYears) {
int yearIndex = 0;
if (amountYears == 1) {
yearIndex == 0;
}
else {
if (year == "2010") {
yearIndex = 0;
}
else if (year == "2011") {
yearIndex = 1;
}
else if (year == "2012") {
yearIndex = 2;
}
else if (year == "2013") {
yearIndex = 3;
}
else if (year == "2014") {
yearIndex = 4;
}
else if (year == "2015") {
yearIndex = 5;
}
}
if (field == "team_name") {
if (order == "decr") {
cout << "\n\nDecreasing Order" << endl;
for (int i = 0; i < NO_TEAMS; i++) {
cout << ptr[yearIndex].teams[i].team_name;
}
}
else if (order == "incr") {
cout << "\n\nIncreasing Order" << endl;
for (int i = 0; i < NO_TEAMS; i++) {
cout << ptr[yearIndex].teams[NO_TEAMS - 1 - i].team_name;
}
}
}
else if (field == "games") {
if (order == "decr") {
quicksortGames(ptr, 0, NO_TEAMS - 1, yearIndex, order);
cout << "TEAM" << "\t\t" << "Number Of Games Decreasing";
for (int i = 0; i < NO_TEAMS; i++) {
cout << ptr[yearIndex].teams[i].team_name << " " << ptr[yearIndex].teams[NO_TEAMS - 1 - i].games;
}
}
else if (order == "incr") {
quicksortGames(ptr, 0, NO_TEAMS - 1, yearIndex, order);
cout << "TEAM" << "\t\t" << "Number Of Games Increasing";
for (int i = 0; i < NO_TEAMS; i++) {
cout << ptr[yearIndex].teams[NO_TEAMS - 1 - i].team_name << " " << ptr[yearIndex].teams[i].games;
}
}
}
Then in this function, I am sorting the code based on the field it is in and in incrementing/decrementing order.
void quicksortGames(annual_stats* pointer, int firstIndex, int lastIndex, int yearIndex, string order)
{
//declaring index variables
int pivotIndex, temp, index1, index2;
if(firstIndex < lastIndex)
{
//assigning first element index as pivot element
pivotIndex = pointer[yearIndex].teams[firstIndex].games;
index1 = pointer[yearIndex].teams[firstIndex].games;
index2 = pointer[yearIndex].teams[lastIndex].games;
//Sorting in Ascending order with quick sort
while(index1 < index2)
{
while(pointer[yearIndex].teams[index1].games <= pointer[yearIndex].teams[pivotIndex].games && index1 < lastIndex)
{
index1++;
}
while(pointer[yearIndex].teams[index2].games <= pointer[yearIndex].teams[pivotIndex].games)
{
index2--;
}
if(index1<index2)
{
//Swapping opertation
temp = pointer[yearIndex].teams[index1].games;
pointer[yearIndex].teams[index1].games = pointer[yearIndex].teams[index2].games;
pointer[yearIndex].teams[index2].games = temp;
}
}
//At the end of first iteration, swap pivot element with index2 element
temp = pointer[yearIndex].teams[pivotIndex].games;
pointer[yearIndex].teams[pivotIndex].games = pointer[yearIndex].teams[index2].games;
pointer[yearIndex].teams[index2].games = temp;
//Recursive call for quick sort, with partiontioning
quicksortGames(pointer, firstIndex, index2-1, yearIndex, order);
quicksortGames(pointer, index2+1, lastIndex, yearIndex, order);
}
}
This function serves to quick sort the games. I made it separately because quick sort is recursive and thus I can't quick sort inside the previous function. I got the quick sort from this website: http://www.cprogramto.com/c-program-quick-sort/ .
So basically, i'm trying to get all the inputs, stick them inside a function that sorts by field/order, and then specifically call the quick sort for the field.
The code compiles but I am currently receiving a segmentation fault 11 error whenever I attempt to run the code with something along the lines of qsort 2015 games decr, etc. When I omit the qsort, my code runs and works for the other sorting algorithms (not shown here) so I am sure the error is within quick sort. Will someone please help me see where exactly my error is?
Consider:
pivotIndex = pointer[yearIndex].teams[firstIndex].games;
index1 = pointer[yearIndex].teams[firstIndex].games;
index2 = pointer[yearIndex].teams[lastIndex].games;
...
while(pointer[yearIndex].teams[index1].games <= pointer[yearIndex].teams[pivotIndex].games && index1 < lastIndex)
You set the array index (index1, index2) to the number of games .
That's not guaranteed to be less than the # of elements in the teams array.
So you wind up accessing the teams array out of bounds == segfault.
More Info: Compare your code to the site you got the algorithm from:
...
index2 = lastIndex;
//Sorting in Ascending order with quick sort
while(index1 < index2)
{
while(array[index1] <= array[pivotIndex] && index1 < lastIndex)
{
index1++;
....
Index is the position in the array, where array[index] is the value . In your case, you are doing the comparison in the (inner) while loop correctly:
while(pointer[yearIndex].teams[index1].games <= pointer[yearIndex].teams[pivotIndex].games && index1 < lastIndex)
but you set the indexes incorrectly:
index1 = pointer[yearIndex].teams[firstIndex].games;
To make it more concrete, suppose there were 10 teams, but the first team (team #0) played 1000 games. Then your code does this:
index1 = pointer[yearIndex].teams[0].games; // index1=1000
while(pointer[yearIndex].teams[1000].games <=
pointer[yearIndex].teams[1000].games && 1000 < 9)
The problem is teams[1000] isn't valid if there are only 10 teams and when you access an array out of bounds like this in C, you get a segfault (if you're lucky) or corrupt memory and/or a security bug (if you're unlucky).
Also, the suggestion made in comments to learn a source debugger (GDB, or whatever - depending on your platform) is critical to learning C.
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