C File input & output - c

Question

I made a simple dictionary code, and surfed for an hour, and I found a file I/O code. But my compiler(I use Microsoft visual C++) says my code(unfortunately, the core part of the code) is wrong. but I can't get it. What is actually wrong and why???
/*
DosDic ver 1.0.0 2015-07-03
*/
#include<stdio.h>
#include<string.h>
char key = 0;
FILE *fp; //set a file pointer var
fp = fopen("dicdata.dat","r"); //open a file
int b = 0;
int trial = 0;
char result[];
char searchfor[] = fp; //save a whole list of dictionary in a var
int i;
char sb[]; //var for search in a list
int getsearchtrial(char sb[]){
for(i=0;i=strlen(sb);i++){ //how much I tried to reach to the word
switch((int)searchfor[b]-(int)sb[i]){ //are two alphabets same?
case 0 :
default : i=0;
}
b++; //keep finding in a list
trial++; //try again
}
return trial;
}
int adress;
int mainpage(){
printf("Type what you want to search : ");
scanf("%c",sb[ ]);
getsearchtrial(sb[ ]) - strlen(sb[ ]) = adress; //where the word is located in the list
for(i = adress;i = adress + 30; i++){ //print
printf("%c",searchfor[i]);
}
printf("Thank you for using DosDic ver.1.0!"); //thank you!
}
void main(){ //call all those functions
mainpage();
fclose(fp); //close list
}
//and whats wrong with this? i cant even get it, but it's not working

Answer 1

Multiple issues.
First of all, you can't assign the result of fopen to fp outside the body of a function; you must move fp = fopen("dicdata.dat", "r"); to within the body of one of your functions (getsearchtrial most likely).
Secondly, you don't read from a file by simply assigning a file pointer to an object; you must use a library function like fscanf or fread or fgets. Assuming your file contains a single string of length 80, you'd need to write something like
char searchfor[81] = {0}; // make sure string is initially empty,
// extra space for string terminator
if ( !fgets( searchfor, sizeof searchfor, fp) )
{
// error reading from file
}
Of course, this depends on how your input file is structured. If it contains a list of strings, then you'll need to use a multidimensional array (or some other structure).
Third, when you declare an array, must specify its size before you can use it. result and searchfor are incomplete array definitions.
Finally, this line
getsearchtrial(sb[ ]) - strlen(sb[ ]) = adress;
needs to be reversed; the target of an assignment must be on the left of the assignment operator.
You need to step back and learn how to write C code from the ground up.

Answer 2

There is so much wrong I'm not even going to itemise it all here - most of it seems to stem from your lack of understanding of arrays in C.
Most notably...
You can't declare an array and not initialise it or specify a size.
You can't assign a FILE * to a char array (and expect decent
results).
You can't execute a statement like fp = fopen at the
global scope like you are.
Try this tutorial and you may fix 95% of your problems, then go from there.