Why do I get a segmentation fault here - c

Question

Excuse me for the sloppy code, I am still a beginner. But after putting a long time into this programming question I got from my Uni I don't know where to turn.
The question itself is: we need to read from the "staedte.csv" (which displays the population and cities of German states) and then return an array of strings with the strings formatted like this: The city ***** has a population of ****.
You are supposed to pass in 2 arguments into the cli: the number 100 and the state you want to check the cities and population for: example Bayern (Bavaria).
My plan was to make a 2d array. First I would dynamically allocate the memory for the first one by making a for loop and iterating over the original csv to check how many states in the csv = the state from the arguments. Then I would make a dynamic array using the amount of states in the csv matching. Then I would iterate (with for loop) over the list of matching states and then first check the length of the formatted string then: The city ***** has a population of ****., then allocate that memory and store the pointer to that info in the previously created array. Then I try to print the first item of that array, meaning the pointer.
I checked and there are 8 elements in the csv with Bavaria as their state, but in the for loop
for (j = 0; j < 8; j++)
if j is larger than 4 then I Get a segmentation fault even though the space is supposed to be allocated.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "input3.h"
/* Die Konstanten:
* int MAX_LAENGE_STR - die maximale String Länge
* int MAX_LAENGE_ARR - die maximale Array Länge
* sind input3.c auf jeweils 255 und 100 definiert
*/
int main(int argc, char **argv)
{
if (argc < 3)
{
printf("Aufruf: %s <anzahl> <bundesland>\n", argv[0]);
printf("Beispiel: %s 100 Bayern\n", argv[0]);
printf("Klein-/Großschreibung beachten!\n");
exit(1);
}
// int anzahl = atoi(argv[1]);
char *bundesland = argv[2];
// Statisch allokierter Speicher
char staedte[MAX_LAENGE_ARR][MAX_LAENGE_STR];
char laender[MAX_LAENGE_ARR][MAX_LAENGE_STR];
int bewohner[MAX_LAENGE_ARR];
read_file("staedte.csv", staedte, laender, bewohner);
// printf("%s %s", bundesland, laender[5]);
int CityCounter = 0;
int CopyCounter = 0;
int *CityArray;
CityArray = (int *)malloc(0);
for (int i = 0; i < MAX_LAENGE_ARR; i++)
{
if (strncmp(laender[i], bundesland, strnlen(bundesland, 10)) == 0)
{
CityArray = realloc(CityArray, sizeof(CityArray) + sizeof(int) * 1);
CityArray[CityCounter] = i;
CityCounter++;
}
}
// printf("%d", CityCounter);
char **string = (char **)malloc(CityCounter * sizeof(int));
int j;
printf("%d", (int)sizeof(CityArray));
int numOfCities = (int)sizeof(CityArray);
for (j = 0; j < 8; j++)
{
char buffer[100];
size_t size = snprintf(buffer, 50, "Die Stadt %s hat %d Einwohner.\n", staedte[CityArray[j]], bewohner[CityArray[j]]);
string[j] = malloc(sizeof(char) * size);
// string[j][size] = "\0";
strncpy(string[j], buffer, size);
}
// printf("%s", string[2]);
for (int i = 0; i < numOfCities; i++)
{
printf("%s", string[i]);
}
// write_file(string, sizeof(string));
free(string);
}
this is the code I wrote.
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include "input3.h"
int MAX_LAENGE_STR = 255;
int MAX_LAENGE_ARR = 100;
void write_file(char *result[], int len)
{
FILE *fp = fopen("resultat.txt", "w");
if (fp == NULL)
{
perror("resultat.txt");
exit(1);
}
for (int i = 0; i < len; i++)
{
fprintf(fp, "%s\n", result[i]);
}
fclose(fp);
}
int read_file(char *dateiname, char staedte[][MAX_LAENGE_STR], char laender[][MAX_LAENGE_STR], int bewohner[])
{
FILE *fp = fopen(dateiname, "r");
if (fp == NULL)
{
perror(dateiname);
exit(1);
}
char stadt[MAX_LAENGE_STR];
char land[MAX_LAENGE_STR];
int anzahl;
int i = 0;
int len;
while (fscanf(fp, "\"%[^\"]\";\"%[^\"]\";%d\n", stadt, land, &anzahl) != EOF)
{
if (i >= MAX_LAENGE_ARR)
{
printf("ERROR: Die Datei ist größer als erwartet!");
return i;
}
len = strlen(stadt) + 1;
strncpy(staedte[i], stadt, len - 1);
staedte[i][len - 1] = '\0';
len = strlen(land) + 1;
strncpy(laender[i], land, len - 1);
laender[i][len - 1] = '\0';
bewohner[i] = anzahl;
i++;
}
fclose(fp);
return i;
}
extern int MAX_LAENGE_ARR;
extern int MAX_LAENGE_STR;
void write_file(char *result[], int len);
int read_file(char *dateiname, char staedte[][MAX_LAENGE_STR], char laender[][MAX_LAENGE_STR], int bewohner []);
This code was supplied by our Uni but it should be correct.
So I changed the
char **string = (char **)malloc(CityCounter * sizeof(int)); to char
**string = (char *)malloc(CityCounter * sizeof(char)); and now I don't get null.
But if I once again change the
for (j = 0; j < 4; j++) {}
and modify the j larger then 4 then I get a bus error