i have the following codes for concating many binary files into single file.but it is showing some error which i am not able to understand.

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include <string.h>

int main()
{


FILE *fs,*ft1,*ft2,*ft3,*ft4,*ft5,*ft6,*ft7,*ft8,*ft9,*ft10,*ft11;
char c;
long i,Filesize;


fs=fopen("newfit_1.fit","wb");

i=0;
do{
ft1=fopen("newaarti1.fit","rb");
fseek(ft1,0,SEEK_END);
Filesize=ftell(ft1)-1;
c=getc(ft1);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft1);

i=0;
do{
ft2=fopen("newaarti2.fit","rb");
fseek(ft2,0,SEEK_END);
Filesize=ftell(ft2)-1;
c=getc(ft2);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft2);

i=0;
do{
ft3=fopen("newaarti3.fit","rb");
fseek(ft1,0,SEEK_END);
Filesize=ftell(ft3)-1;
c=getc(ft3);
i=i+1;
fputc(c,fs);
}
while(i<=Filesize);
fclose(ft3);

i=0;
do{
ft4=fopen("newaarti4.fit","rb");
fseek(ft4,0,SEEK_END);
Filesize=ftell(ft4)-1;
c=getc(ft4);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft4);

i=0;
do{
ft5=fopen("newaarti5.fit","rb");
fseek(ft5,0,SEEK_END);
Filesize=ftell(ft5)-1;
c=getc(ft5);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft5);

i=0;
do{
ft6=fopen("newaarti6.fit","rb");
fseek(ft6,0,SEEK_END);
Filesize=ftell(ft6)-1;
c=getc(ft6);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft6);

i=0;
do{
ft7=fopen("newaarti7.fit","rb");
fseek(ft7,0,SEEK_END);
Filesize=ftell(ft7)-1;
c=getc(ft7);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft7);

i=0;
do{
ft8=fopen("newaarti8.fit","rb");
fseek(ft8,0,SEEK_END);
Filesize=ftell(ft8)-1;
c=getc(ft8);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft8);

i=0;
do{
ft9=fopen("newaarti9.fit","rb");
fseek(ft9,0,SEEK_END);
Filesize=ftell(ft9)-1;
c=getc(ft9);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft9);

i=0;
do{
ft10=fopen("newaarti10.fit","rb");
fseek(ft10,0,SEEK_END);
Filesize=ftell(ft10)-1;
c=getc(ft10);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft10);

i=0;
do{
ft11=fopen("newaarti11.fit","rb");
fseek(ft11,0,SEEK_END);
Filesize=ftell(ft11)-1;
c=getc(ft11);
i=i+1;
fputc(c,fs);

}
while(i<=Filesize);
fclose(ft11);
fclose(fs);

getch();
return 0;
}

i wish to read the binary files till one minus from their filesize.so i have used filesize as variable which contains the required size of the file.

can anyone plz help me for the same?
is it possible to make a function which calculates the size of the file and can i call that function each time time i require in main??