Rot13 in C - Printable Version

Code:
#include <stdio.h>



char rotateChar(int oldChar);

void encryptString(char *str);

void encryptFile(FILE *fp, char *name);



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

 

 if(argc < 2) {

  printf("fudge you.\n");

  return 0;

 }



 FILE *fp = fopen(argv[1], "r");



 if(fp == 0) {

  //printf("Couldn't open file for reading\n");

  encryptString(argv[1]);

  return 0;

 } else {

  encryptFile(fp, argv[1]);

  return 0;

 }



}



void encryptFile(FILE *fp, char *name) {

 char writeFp[strlen(name) + 1];

 sprintf(writeFp, "_%s", name);

 

 FILE *encFile = fopen(writeFp, "w");



 if(encFile == 0) {

  printf("couldn't open file for writing.\n");

  return 0;

 }



 char fpChar = fgetc(fp);

 char newChar;

 while(fpChar != EOF) {

  //printf("%c",fpChar);

  newChar = rotateChar(fpChar);

  fputc(newChar, encFile);

  fpChar = fgetc(fp);

 }



 fclose(fp);



 printf("New File is called: %s\n", writeFp);

}



void encryptString(char *str) {

 int i;

 for(i = 0; i < strlen(str); i++) {

  int charAsInt = (int)str[i];

  char newChar = rotateChar(charAsInt);

  str[i] = newChar;

 }



 printf("%s\n",str);

}



char rotateChar(int oldChar) {



 if(oldChar >= 'A' && oldChar <= 'Z') {

  oldChar += 13;

  if(oldChar > 'Z') oldChar -= 26;

 } else if(oldChar >= 'a' && oldChar <= 'z') {

  oldChar += 13;

  if(oldChar > 'z') oldChar -= 26;

 }



 return (char)oldChar;



}



/*

[Massey@Massey C]$ ./FileIO hello

uryyb

[Massey@Massey C]$ echo "hi, han" > no.txt

[Massey@Massey C]$ ./FileIO no.txt

hi, han

[Massey@Massey C]$ cat _no.txt

uv, una

[Massey@Massey C]$

*/