Add more than one patient C Pointers - c

Question

I'm having trouble with my pointers. I'm trying to add multiple patients to my list. I know how to do it, it's just that the code gives me seg faults.
Here is the code in question:
void addPatient(int patientID) {
Chartptr patients_chart;
patients_chart = getChart(patientID);
// if patient wasn't found, add new patient
if (patients_chart == NULL) {
Chartptr new_chart;
// allocate and initialize new patient
new_chart = (Chartptr)malloc(sizeof(Chart));
new_chart->id = patientID;
new_chart->buffer = NULL;
// insert new patient into list
new_chart->next = patientList;
patientList = new_chart;
// test print patient data
printf("%d %d\n", new_chart->id, patientList->id);
}
}
/*
* getChart: given a patientID, return a pointer to their Chart
*/
Chartptr getChart(int patientID) {
Chartptr foundChart = NULL;
// find the patient chart with id
foundChart = patientList;
if (foundChart != NULL) {
while(foundChart->id != patientID) {
foundChart = foundChart->next;
}
}
return foundChart;
}
Here are the structs:
/*
* Patient's health chart: ID + linked list of health type readings
*/
typedef struct chartEntry* Chartptr; /* pointer to a Chart */
typedef struct chartEntry{
int id; /* patient ID */
CBuffptr buffer; /* pointer to first health type buffer */
Chartptr next; /* pointer to next patient */
}Chart;
extern Chartptr patientList; /* global declaration for start of the patient chart linked list */
I'm sending to the add patient, id, which I get from main, that much I know works perfectly.
But for some reason when the patientList is not NULL and it enters the while loop it seg faults or its after the while loop in the rest of addPatient. I don't know which. Thanks for your help.

Answer 1

I think here is your error:
while(foundChart->id != patientID) {
foundChart = foundChart->next;
You are updating foundChart but never checking in the while loop if it had become NULL, in case no patientID matches.

Answer 2

getChart() has no condition stop it running off the end of the list if no match is found.

Answer 3

Please update code as given below it will work :D
Chartptr getChart(int patientID) {
Chartptr foundChart = NULL;
// find the patient chart with id
foundChart = patientList;
while(foundChart!= NULL) {
if(foundChart->id == patientID) {
return foundChart;
}
foundChart = foundChart->next;
}
return NULL;
}