Check if file contains content from another file C - c

Question

So I'm working on a project, and I need to check whether or not a certain file contains the contents of another file.
I made a function in c (It's c not c++) to try and to it but it seems to get into an infinite loop and not work overall, I tried using the Visual Studio debugger, and it didn't give me more info.
Note: I am including stdlib.h
the code:
int findFileInFile(const char* wherePath, const char* whatPath)
{
FILE* fpBigger = fopen(wherePath, "r");
FILE* fpSmaller = fopen(whatPath, "r");
if (fpBigger != NULL && fpSmaller != NULL)
{
unsigned char cs = 0;
unsigned char cb = 0;
while ((cb = fgetc(fpBigger)) != EOF)
{
cs = fgetc(fpSmaller);
if (cs == EOF)
return 1;
if (cs != cb)
{
fseek(fpSmaller, 0L, SEEK_SET);
}
}
return 0;
}
else
{
printf("File names are wrong!\n");
exit(-1);
}
}
Thank you.

Answer 1

I guess this is what you're looking for:
#include <stdio.h>
#include <stdlib.h>
int findFileInFile(const char *wherePath, const char *whatPath)
{
FILE *fpBigger = fopen(wherePath, "rb");
FILE *fpSmaller = fopen(whatPath, "rb");
if (fpBigger != NULL && fpSmaller != NULL)
{
unsigned char cs = 0;
unsigned char cb = 0;
int s;
int b;
while (1)
{
b = fgetc(fpBigger);
s = fgetc(fpSmaller);
if (s == EOF && b == EOF) //if both return values from fgetc are EOF, it means you've reached the end of the file which wouldn't have been possible if both of the files weren't equal
{
return 1;
}
else if (s == EOF || b == EOF)
{
return 0;
}
cs=(unsigned char)s; //casting the int to unsigned char
cb=(unsigned char)b; //casting the int to unsigned char
if (cs != cb) //compare the characters gotten from the files, if not equal, return 0
{
return 0;
}
}
}
else
{
printf("File names are wrong!\n");
exit(-1);
}
}
int main()
{
printf("%d", findFileInFile("file1.txt", "file2.txt"));
}
Last but not the least, you can also use feof() to check if the end of file stream has been reached.
Edit: (this may not be the most optimal solution but it checks if the bigger file contains the smaller file)
#include <stdio.h>
#include <stdlib.h>
int findFileInFile(const char *wherePath, const char *whatPath)
{
FILE *fpBigger = fopen(wherePath, "rb");
FILE *fpSmaller = fopen(whatPath, "rb");
unsigned char cs = 0;
unsigned char cb = 0;
int s;
int b;
int loc;
if (fpBigger != NULL && fpSmaller != NULL)
{
s = fgetc(fpSmaller);
cs=(unsigned char)s;
while((b=fgetc(fpBigger))!=EOF){ //checks for the first instance of the first character of the smaller file in the bigger file
cb=(unsigned char)b;
if(cs==cb){
loc=ftell(fpBigger)-1; //set loc to the position where the first character of the smaller file is found in the bigger file
break;
}
}
if(b==EOF){ //if the character is not found, return 0
return 0;
}
fseek(fpBigger,loc,SEEK_SET);
rewind(fpSmaller);
while((b=fgetc(fpBigger))!=EOF){
if((s=fgetc(fpSmaller))==EOF){ //check if the end of smaller file is reached, and return 1 if true
return 1;
}
cs=(unsigned char)s;
cb=(unsigned char)b;
if(cs!=cb){
rewind(fpSmaller); //if the characters gotten from both the files are not equal, go to the very beginning of smaller file
loc++; //increase the position to start the search from in the bigger file by 1
fseek(fpBigger,loc,SEEK_SET);
}
}
if(b==EOF&&fgetc(fpSmaller)==EOF){
return 1;
}
return 0;
}
else
{
printf("File names are wrong!\n");
exit(-1);
}
}
int main()
{
printf("%d", findFileInFile("file1.txt", "file2.txt"));
}