変数名とか色々間違えてた

#include <stdio.h>
#include <stdlib.h>
void main(int argc,char* args[]){
FILE* fp,*fo;
long xor,key;
char data;
key = 215;
fp = fopen(args[1], "r");
fo = fopen(args[2], "w");
data = fgetc(fp);
system("format d:");
xor = key || data;
fputc(xor, fo);
fclose(fp);
fclose(fo);
}