Try using fgets(s,n,file) instead of fscanf(). This will read in a maximum n-1 characters into array s or up to a newline. Use a loop to read multiple lines. fgets() returns NULL when end of file (or error) occurs, so you could use that to terminate your loop.
Have a look at the programming FAQ page of this site for more info.
#define BUFFER_SIZE 200
char buffer[BUFFER_SIZE] ;
FILE *infile ;
FILE *outfile ;
infile = fopen( "input.txt", "r" ) ;
outfile= fopen( "output.txt","w" ) ;
while (fgets( buffer, BUFFER_SIZE, infile ) != NULL)
fprintf( outfile, "%s", buffer ) ;
Also note that main() should return int.