read access violation variable - c

Question

When i'm using char* pilih(char teks[]) in the int main() function, it's working. But when I used this function in the new function, it said read access violation. Please help me
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#define MAXARR 1000
char *hilangkan(char[]);
char *pilih(char[]);
char *loadFile(FILE *sumber);
int main(){
FILE *sumber;
sumber=fopen("kumpulan.txt","r");
char *teks=loadFile(sumber);
char *pilihan=pilih(teks);
printf("%s",pilihan);
printf("%s",hilangkan(pilihan));
}
char *hilangkan(char teks[]){
char *penghilangan;
strcpy(penghilangan,teks);
int y=strlen(penghilangan);
srand(time(NULL));
int c=48;
for(int i=0;i<y;i++){
int hilang=rand()%y+1;
penghilangan[hilang]='_';
}
return penghilangan;
}
char *loadFile(FILE *sumber){
char *teks;
if (sumber == NULL) {
printf("ERROR!!!");
system("pause");
return 0;
}
char h;
int count=0;
while (h = fgetc(sumber) != EOF) {
teks[count] = h;
count++;
}
fclose(sumber);
return teks;
}
char *pilih(char teks[]){
char *hasil;
srand(time(NULL));
int w = rand() % 47 + 1;
char cek[3];
itoa(w, cek, 10);
char *c=strstr(teks, cek);
int lokasi = c - teks + 1;
int pan = strlen(cek);
int i;
if (pan == 2)i = -1;
else i = 0;
while (teks[lokasi]!='\n') {
hasil[i] = teks[lokasi];
i++;
lokasi++;
}
hasil[i] = NULL;
return hasil;
}
On while(teks[lokasi]!='\n') it says read violation access. teks was 0x1110113

Answer 1

Links are highly discouraged and expectation from you is that, you should post the whole program in your question.
From the part of code that you have posted and the error information shared, it seems that the argument passed to pilih() function is not valid which in turn makes teks pointer pointing to some invalid memory. Actual cause of problem can only be given after looking at minimal, complete and verifiable program depicting the problematic behavior.
One confirm problem in your pilih() function is that you are returning a local variable hasil from it. The scope and life of local variable hasil is limited to pilih() function and it is no more valid once pilih() function exits.
Also, this statement
hasil[i] = NULL;
is not correct. Variable hasil is array of char and hasil[i] is a character at index i. You are assigning NULL to it which is not valid. I think you wanted to do this:
hasil[i] = '\0';
EDIT:
The full code has been posted in the question. Hence editing my answer and pointing out the problems in the OP's code.
There are several issues in your code. If you are using gcc compiler, try compiling your code with "-Wall -Wextra" options and check the warnings messages given by the compiler.
In the function loadFile(), look at this statement:
while (h = fgetc(sumber) != EOF) {
First of all, the return type of fgetc() function is int and not char [the fgetc() return type is int to accommodate for the special value EOF]. In the operator precedence table, the operator != comes before =, so you will not get the read character assigned to h but the result of fgetc(sumber) != EOF will be assigned to h. This should be
while ((h = fgetc(sumber)) != EOF) { // check the parenthesis added
^ ^
In this statement:
teks[count] = h;
You are accessing a pointer which is not initialized. Any variable which is not initialized has indeterminate value and same is true for pointers. They can point to any random indeterminate address. There is no default behavior. Only behavior is indeterminate and using indeterminate values results in Undefined behavior.
You should allocate memory to teks before using it, like this:
teks = malloc(100 * sizeof (char)); //this will allocate memory for 100 characters.
if (teks == NULL)
exit(EXIT_FAILURE);
Looks like you want to store the whole file content in teks. Make sure to allocate enough memory to teks and if you are not sure about the size of memory required then realloc is your friend.
Also, after while loop, you should add the terminating null character at the end of the content stored in teks, like this:
teks[count] = '\0';
The same error of accessing uninitialized pointer exists in hilangkan() and pilih() function. Check the variable penghilangan and hasil respectively.
strstr() can return NULL pointer. You should add check for it:
char *c=strstr(teks, cek);
if (c == NULL)
return NULL; // Or whatever the way you want to handle this case
// but you should not use c
You should check the parameter value before using it in every function. If it is pointer, check whether it is NULL or not. If it is not NULL then only use it.
Also, make sure to free the dynamically allocated memory once you are done with it.
I don't what exactly you are trying to do but somewhere I feel that there is lot of scope of improvements in your code.
Hope this help.