Dynamically allocated Array of pointers to structures - c

Question

I am trying to allocate enough space for an array of pointers to structure(City) with
City **ptrArray = (City **)calloc(numberOfLines, sizeof(City*));
char tempArray[100];
char* temp = tempArray;
int slength;
for (int i = 0; i < numberOfLines; i++)
{ //Allocates enough memory for array of length of string
fscanf(fPtr, "%99[^:] %*c", tempArray);
slength = strlen(temp);
ptrArray[i] = (City*)malloc(sizeof(int)+(sizeof(char)*slength));
strcpy(ptrArray[i]->cityName, temp);
//fscanf(fPtr, "%d", ptrArray[i]->temperature);
}
This is where I read the data from a file into the array. The debugger(visual studio) only shows one cell in ptrArray and it seems that the data gets lost.
numberOfLines is an assigned int value.
tempArray is a temporary holding place for the strings read from the file.
temp is a pointer to tempArray.
Bonus issue: The commented out line at the bottom of the for loop breaks the code every time and I have no clue why.
edit: I added the code where I initialized temp and tempArray.
Also it is a weird call to malloc because the assignment specifies allocating exactly enough memory for the string and an int instead of having a maximum value for the string. And here is my struct
typedef struct{
int temperature;
char cityName[100];
}City;
Thank you very much for you help!

Answer 1

For dynamic allocation of cityName.
typedef struct{
int temperature;
char *cityName;// pointer to char
}City;
City **ptrArray = calloc(numberOfLines, sizeof(City*));
if ( ptrArray == NULL) {
printf ( "calloc failed\n");
exit(1);
}
char tempArray[100];
int slength;
for (int i = 0; i < numberOfLines; i++)
{
if ( ( fscanf(fPtr, "%99[^:] %*c", tempArray)) != 1) {
//handle problem - break or return or exit.
}
slength = strlen(tempArray);
ptrArray[i] = malloc( sizeof(City));// memory for structure
if ( ptrArray[i] == NULL) {
printf ( "malloc failed\n");
exit ( 1);
}
ptrArray[i]->cityName = malloc( 1 + slength));// memory for cityName + 1 for '\0'
if ( ptrArray[i]->cityName == NULL) {
printf ( "malloc failed\n");
exit (1);
}
strcpy(ptrArray[i]->cityName, tempArray);
if ( ( fscanf(fPtr, "%d", &ptrArray[i]->temperature)) != 1) {
//handle problem break or return or exit
}
}
Memory allocated should also be freed when it is no longer needed. numberOfLines and ptrArray may have different names outside this function and the corresponding names would be used instead.
for ( i = 0; i < numberOfLines; i++) {
free ( ptrArray[i]->cityName);
free ( ptrArray[i]);
}
free ( ptrArray);