Simple encryption and decryption in C that I once made.

crypt.c

#include <stdio.h>
#include <string.h>
typedef enum {
	encrypt,
	decrypt
}intent;

int main(int argc, const char*argv[]) {
	intent which = strncmp(argv[2], "e",1) == 0? encrypt : decrypt;

	int dir = which == decrypt ? -1 : 1;

	if (argv[1]) {
		printf("%s%c",(which==decrypt ? "Decrypted string:" : "Encrypted String:"), argv[1][0]);

		for(int i = 1; i < strlen(argv[1]); i++) {
			char puts = argv[1][i] + (i * dir);
			printf("%c",puts);
		}
		printf("\n");
	} else
		printf("Error ~ No preferences specified");
}