Characters

In java, the primitive char type stores single characters. Note: please do NOT include an ascii table on your cheat sheet as we will provide that for you. Let's look at an example of a character in java:

char someChar = 'a';
char someOtherChar = '~';

Character range

According to the rules, we will only be dealing with the characters from ' ' to '~' (space to tilde). In order to understand what this really means, lets look at an ascii table:

(source: https://commons.wikimedia.org/wiki/File:ASCII-Table-wide.svg\)

sFrom this table, we can see that we only deal with the characters from 32 to 126 . You might have also noticed that characters correspond to decimal and hexadecimal values. That means that in java you can do something like this:

char a = (char)32;         // the ' ' character (space)
char b = (char)76;         // the 'L' character 
char c = (char)0x4D;       // the 'M' character
char d = (char)0101;       // the 'A' character
char e = (char)0b1001111;  // the 'O' characte

Exercises

1. What character is represented by the decimal value 40 ?
2. What character is represented by the octal value 40?
3. What character is represented by the hexadecimal value 40 ?
4. What is 'T' in decimal?
5. What is 'O' in octal?
6. What is 'P' in hexadecimal?

Escape Sequences

The rules also mention that we can use the following escape sequences: \\, \', \" . Lets look at how these are parsed in java:

char backslash = '\\';  // This will be printed like this: \
char singquote = '\'';  // This will be printed like this: '
char doubquote = '\"';  // This will be printed like this: "

Exercises

1. How is "I am a coo\\ dude" printed?
2. How is "This is a \"great\" guide" printed?
3. How is "It\'s or It is?" printed?
4. How is "\\33tc0d3" printed?
5. How is "\"\"" printed?
6. How is "\'\'\'" printed?

Character arithmetic

The rules also say you can perform character arithmetic, but only if the result is in the range from '0' to '9' , or from 'A' to 'Z' , or from 'a' to 'z' . Lets look into some examples of character arithmetic:

char cd    = 'c' + 'd' - '`'; // The resulting character is 'g'
char char7 = '3' + '4' - '0'; // The resulting character is '7'
char CD    = 'C' + 'D' - '@'; // The resulting character is 'G'

The way this arithmetic works is char s are basically 8 bit integers, and it does the arithmetic on the integer values and 'converts' it back to a character.

Exercises

1. What is (char)('7' * 2) ?
2. What is (char)(0x20 + 77) ?
3. What is (char)('6' + 'C') ?
4. What is (char)('z' - '\"') ?
5. What is (char)('d' - '1') ?
6. What is (char)('!' + '!' + '\"') ?