Caesar

some of the code I've written is so stupid I tell you.

this one basically fires up a REPL with a argv[1] as the number of forward caesar cipher steps you want to take.

really not worth running.

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

int upper(int character, int shift) {
	character += shift;
	if (character > 90) {
		character = (character-90)%26 + 64;
	}
	else if (character < 65) {
		character = (65-character)%26;
		if (character == 0) return 65;
		character = 91 - character;
	}
	return character;
}

int lower(int character, int shift) {
	character += shift;
	if (character > 122) {
		character = (character-122)%26 + 96;
	}
	else if (character < 97) {
		character = (97-character)%26;
		if (character == 0) return 97;
		character = 123 - character;
	}
	return character;
}


int main(int argc, char* argv[]) {
	int shift = atoi(argv[1]);
	int character = getchar();
	while (character != EOF) {
		if (character >= 'A' && character <= 'Z') {
			putchar(upper(character, shift));
		}
		else if (character >= 'a' && character <= 'z') {
			putchar(lower(character, shift));
		}
		else putchar(character);
		character = getchar();
	}
}

File XOR 

#include <stdio.h>

int main(int argc, char *argv[])
{
    FILE *fi, *fo;
    char *cp;
    int c;

    if ((cp = argv[1]) && *cp!='\0') {
        if ((fi = fopen(argv[2], "rb")) != NULL) {
            if ((fo = fopen(argv[3], "wb")) != NULL) {
                while ((c = getc(fi)) != EOF) {
                    if (!*cp) cp = argv[1];
                    c ^= *(cp++);
                    putc(c,fo);
                }
                fclose(fo);
            }
            fclose(fi);
        }
    }
}