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fix: declared x variable (#36046)

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Randell Dawson
2019-05-14 23:19:44 -07:00
committed by The Coding Aviator
parent aad311a76f
commit b013f2ab3a
1 changed files with 41 additions and 56 deletions
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97
guide/english/certifications/javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher/index.md
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@ -1,18 +1,6 @@
---
title: Caesars Cipher
---
![:triangular_flag_on_post:](https://forum.freecodecamp.com/images/emoji/emoji_one/triangular_flag_on_post.png?v=3 ":triangular_flag_on_post:") Remember to use <a>**`Read-Search-Ask`**</a> if you get stuck. Try to pair program ![:busts_in_silhouette:](https://forum.freecodecamp.com/images/emoji/emoji_one/busts_in_silhouette.png?v=3 ":busts_in_silhouette:") and write your own code ![:pencil:](https://forum.freecodecamp.com/images/emoji/emoji_one/pencil.png?v=3 ":pencil:")
### ![:checkered_flag:](https://forum.freecodecamp.com/images/emoji/emoji_one/checkered_flag.png?v=3 ":checkered_flag:") Problem Explanation:
* You need to write a function, which will take a string encoded with _Caesar cipher_ as a parameter and decode it.
* The one used here is ROT13 where the value of the letter is shifted by 13 places. e.g. 'A' ![:left_right_arrow:](https://forum.freecodecamp.com/images/emoji/emoji_one/left_right_arrow.png?v=3 ":left_right_arrow:") 'N', 'T' ![:left_right_arrow:](https://forum.freecodecamp.com/images/emoji/emoji_one/left_right_arrow.png?v=3 ":left_right_arrow:") 'G'.
* You have to shift it back 13 positions, such that 'N' ![:left_right_arrow:](https://forum.freecodecamp.com/images/emoji/emoji_one/left_right_arrow.png?v=3 ":left_right_arrow:") 'A'.
#### Relevant Links
* <a href='http://forum.freecodecamp.com/t/javascript-string-prototype-charcodeat/15933' target='_blank' rel='nofollow'>String.prototype.charCodeAt</a>
* <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCharCode' target='_blank' rel='nofollow'>String.fromCharCode</a>
## ![:speech_balloon:](https://forum.freecodecamp.com/images/emoji/emoji_one/speech_balloon.png?v=3 ":speech_balloon:") Hint: 1
@ -40,27 +28,26 @@ Leave anything that doesn't come between A-Z as it is.
## ![:beginner:](https://forum.freecodecamp.com/images/emoji/emoji_one/beginner.png?v=3 ":beginner:") Basic Code Solution:
```javascript
function rot13(str) {
// Split str into a character array
return str.split('')
// Iterate over each character in the array
.map.call(str, function(char) {
// Convert char to a character code
x = char.charCodeAt(0);
// Checks if character lies between A-Z
if (x < 65 || x > 90) {
return String.fromCharCode(x); // Return un-converted character
}
//N = ASCII 78, if the character code is less than 78, shift forward 13 places
else if (x < 78) {
return String.fromCharCode(x + 13);
}
// Otherwise shift the character 13 places backward
return String.fromCharCode(x - 13);
}).join(''); // Rejoin the array into a string
}
function rot13(str) {
// Split str into a character array
return str.split('')
// Iterate over each character in the array
.map.call(str, function(char) {
// Convert char to a character code
var x = char.charCodeAt(0);
// Checks if character lies between A-Z
if (x < 65 || x > 90) {
return String.fromCharCode(x); // Return un-converted character
}
//N = ASCII 78, if the character code is less than 78, shift forward 13 places
else if (x < 78) {
return String.fromCharCode(x + 13);
}
// Otherwise shift the character 13 places backward
return String.fromCharCode(x - 13);
}).join(''); // Rejoin the array into a string
}
```
![:rocket:](https://forum.freecodecamp.com/images/emoji/emoji_one/rocket.png?v=3 ":rocket:") <a href='https://repl.it/CLjU/38' target='_blank' rel='nofollow'>Run Code</a>
### Code Explanation:
@ -72,33 +59,33 @@ Leave anything that doesn't come between A-Z as it is.
#### Relevant Links
* <a href='http://forum.freecodecamp.com/t/javascript-array-prototype-map/14294' target='_blank' rel='nofollow'>Array.prototype.map</a>
* <a href='http://forum.freecodecamp.com/t/javascript-string-prototype-split/15944' target='_blank' rel='nofollow'>String.prototype.split</a>
* <a href='http://forum.freecodecamp.com/t/javascript-array-prototype-join/14292' target='_blank' rel='nofollow'>Array.prototype.join</a>
* <a href='https://forum.freecodecamp.com/t/javascript-array-prototype-map/14294' target='_blank' rel='nofollow'>Array.prototype.map</a>
* <a href='https://forum.freecodecamp.com/t/javascript-string-prototype-split/15944' target='_blank' rel='nofollow'>String.prototype.split</a>
* <a href='https://forum.freecodecamp.com/t/javascript-array-prototype-join/14292' target='_blank' rel='nofollow'>Array.prototype.join</a>
## ![:sunflower:](https://forum.freecodecamp.com/images/emoji/emoji_one/sunflower.png?v=3 ":sunflower:") Intermediate Code Solution:
```javascript
// Solution with Regular expression and Array of ASCII character codes
function rot13(str) {
var rotCharArray = [];
var regEx = /[A-Z]/ ;
str = str.split("");
for (var x in str) {
if (regEx.test(str[x])) {
// A more general approach
// possible because of modular arithmetic
// and cyclic nature of rot13 transform
rotCharArray.push((str[x].charCodeAt() - 65 + 13) % 26 + 65);
} else {
rotCharArray.push(str[x].charCodeAt());
}
}
str = String.fromCharCode.apply(String, rotCharArray);
return str;
// Solution with Regular expression and Array of ASCII character codes
function rot13(str) {
var rotCharArray = [];
var regEx = /[A-Z]/;
str = str.split("");
for (var x in str) {
if (regEx.test(str[x])) {
// A more general approach
// possible because of modular arithmetic
// and cyclic nature of rot13 transform
rotCharArray.push((str[x].charCodeAt() - 65 + 13) % 26 + 65);
} else {
rotCharArray.push(str[x].charCodeAt());
}
}
str = String.fromCharCode.apply(String, rotCharArray);
return str;
}
// Change the inputs below to test
rot13("LBH QVQ VG!");
// Change the inputs below to test
rot13("LBH QVQ VG!");
```
### Code Explanation:
@ -146,8 +133,6 @@ Leave anything that doesn't come between A-Z as it is.
* <a href='https://forum.freecodecamp.com/t/regular-expressions-resources/15931' target='_blank' rel='nofollow'>Regex</a>
* <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/test' target='_blank' rel='nofollow'>Regex.test</a>
![:rocket:](https://forum.freecodecamp.com/images/emoji/emoji_one/rocket.png?v=3 ":rocket:") <a href='https://repl.it/CLjU/39' target='_blank' rel='nofollow'>Run Code</a>
## ![:rotating_light:](https://forum.freecodecamp.com/images/emoji/emoji_one/rotating_light.png?v=3 ":rotating_light:") Advanced Code Solution:
function rot13(str) { // LBH QVQ VG!