Programming

Converting from String to Numeric

The functions listed in this table provide a number of ways to convert character strings to numeric data.

Function	Description	Example
uintN (e.g., uint8)	Convert a character to an integer code that represents that character.	'Hi' 72 105
str2num	Convert a character type to a numeric type.	'72 105' [72 105]
str2double	Similar to str2num, but offers better performance and works with cell arrays of strings.	{'72' '105'} [72 105]
hex2num	Convert a numeric type to a character type of specified precision, returning a string that MATLAB can evaluate.	'A' '-1.4917e-154'
hex2dec	Convert a character type of hexadecimal base to a positive integer.	'A' 10
bin2dec	Convert a positive integer to a character type of binary base.	'1010' 10
base2dec	Convert a positive integer to a character type of any base from 2 through 36.	'12' 10 (if base == 8)

Converting from a Character Equivalent

Character arrays store each character as a 16-bit numeric value. Use one of the integer conversion functions (e.g., uint8) or the double function to convert strings to their numeric values, and char to revert to character representation:

• name = 'Thomas R. Lee';
  
  name = double(name)
  name =
      84  104  111  109  97  115  32  82  46  32  76  101  101
  
  name = char(name)
  name =
     Thomas R. Lee
  

Converting from a Numeric String

Use str2num to convert a character array to the numeric value represented by that string:

• str = '37.294e-1';
  
  val = str2num(str)
  val =
      3.7294
  

The str2double function converts a cell array of strings to the double-precision values represented by the strings:

• c = {'37.294e-1'; '-58.375'; '13.796'};
  
  d = str2double(c)
  d =
      3.7294
    -58.3750
     13.7960
  
  whos
    Name      Size                   Bytes  Class
  
    c         3x1                      224  cell array
    d         3x1                       24  double array
  

Converting from a Specific Radix

To convert from a character representation of a nondecimal number to the value of that number, use one of these functions: hex2num, hex2dec, bin2dec, or base2dec.

The hex2num and hex2dec functions both take hexadecimal (base 16) inputs, but hex2num returns the IEEE double-precision floating-point number it represents while hex2dec converts to a decimal integer.

Converting from Numeric to String

Function Summary

© 1994-2005 The MathWorks, Inc.