ToC | Next Labs: Error Correction and Compression. Part 1. Math Alive

ASCII Encoding


ASCII stands for American Standard Code for Information Interchange. It is a standard numerical coding used by almost every computer that assigns numbers to every symbol and character that can be inputted or outputted. (That includes lower and upper case letters, numbers, punctuation signs, and other symbols.) In decimal ASCII, every symbol and character corresponds to a number written in base 10 (that is, our everyday notation for numbers). There also exists a binary ASCII notation, which uses only the binary numbers we saw in Lab 1, which have only 1's and 0's in their digits.

A computer displays and relates information in terms of ASCII character codes, but in the end only the actual binary translation is what the computer uses.

For historical reasons 127 numbers were used to assign symbols to (127 is the biggest number you can have using only seven digits in binary notation). The order of characters in ASCII code is as follows:

  • control characters
  • the space character (number 32)
  • symbols
  • numerals in increasing order
  • more symbols
  • uppercase letters (in alphabetical order)
  • more symbols
  • lowercase letters (in alphabetical order)
  • more symbols
  • the Del (null) character
We will first look at a conversion from letters and symbols to numbers in base 10. Here is a table that shows the ASCII encoding in the range 33 to 127.

ASCII Encoding


    0     1     2     3     4     5     6     7     8     9  
30         !   "   #   $   %   &   '
40   (   )   *   +   ,   -   .   /   0   1
50   2   3   4   5   6   7   8   9   :   ;
60   <   =   >   ?   @   A   B   C   D   E
70   F   G   H   I   J   K   L   M   N   O
80   P   Q   R   S   T   U   V   W   X   Y
90   Z   [   \   ]   ^   _   `   a   b   c
100   d   e   f   g   h   i   j   k   l   m
110   n   o   p   q   r   s   t   u   v   w
120   x   y   z   {   |   }   ~   Del    

You can practice ASCII encoding below. Please, input decimals without leading zeros, and put exactly one space between decimals. Example: "Math Alive!" is encoded as "77 97 116 104 32 65 108 105 118 101 33". After typing in your answer, press return to see if you are correct:

Practice
ASCII Encoding

ToC | Next Last Modified: August 2008