XOR File using c

xorfile.c

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string>

int PasswordKey(char *pws){
	int x = 0;
	size_t i = 0;
	x = 1586;

	while (pws[i]){
		x += (int)pws[i];
		i++;
	}

	return x;
}

int main(int argc, char *argv[])

{
	FILE *fp1 = nullptr;
	FILE *fp2 = nullptr;
	char c = '\0';
	int key = 0;

	//Check syntax of command
	if (argc < 4){
		fprintf(stdout, "Usage input-file output-file password.\n");
		return EXIT_FAILURE;
	}

	//Check for password
	if (strlen(argv[3]) == 0){
		fprintf(stdout,"Password Required.\n");
		return EXIT_FAILURE;
	}

	//Open input file.
	fp1 = fopen(argv[1], "rb");

	//Check that file is opened
	if (fp1 == NULL){
		fprintf(stdout,"The Input File Was Not Found.\n");
		return EXIT_FAILURE;
	}

	//Open output file for writeing.
	fp2 = fopen(argv[2], "wb");

	//Check that output file was created.
	if (!fp2){
		fprintf(stdout,"Cannot Write To Output File.\n");
		_fcloseall();
		return EXIT_FAILURE;
	}

	//Read input file data
	srand(PasswordKey(argv[3]));

	while (!feof(fp1)){
		//Get char from input
		c = getc(fp1);

		if (!feof(fp1)){
			//Get random value from key
			key = rand() % 255;
			//Xor key with current char
			key ^= c;
			//Write char to output file.
			fputc((char)key, fp2);
		}
	}

	//Close opened files
	_fcloseall();

	return EXIT_SUCCESS;

}

I would use fcloseall() instead of fclose(). How you probably could guess by the name it closes all files in one Command. What I also would change is the return values.. instead of 1 or 0 I´d be using EXIT_FAILURE / EXIT_SUCCESS, however this doesn´t change anything it´s just in my opinion a better way to do it. Last but not least, I´d also change all of that printf() commands into fprintf(), the only diffrence here is, that it´s much safer to work with and the first parameter is where the txt should be displayed on.
Otherwise great job!

Thanks Rick for the info I now had time to update the changes you said I also done a few other minor tweaks.