String Conversions - GNU Octave
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### 5.6 String Conversions

Octave supports various kinds of conversions between strings and numbers. As an example, it is possible to convert a string containing a hexadecimal number to a floating point number.

         hex2dec ("FF")
              ⇒ ans = 255

— Function File: bin2dec (s)

> Return the decimal number corresponding to the binary number represented by the string s. For example:

>               bin2dec ("1110")
>                    ⇒ 14

> If s is a string matrix, return a column vector of converted numbers, one per row of s. Invalid rows evaluate to NaN.

> See also: dec2bin, base2dec, hex2dec.

— Function File: dec2bin (d, len)

> Return a binary number corresponding to the non-negative integer d, as a string of ones and zeros. For example:

>               dec2bin (14)
>                    ⇒ "1110"

> If d is a vector, returns a string matrix, one row per value, padded with leading zeros to the width of the largest value.

> The optional second argument, len, specifies the minimum number of digits in the result.

> See also: bin2dec, dec2base, dec2hex.

— Function File: dec2hex (d, len)

> Return the hexadecimal string corresponding to the non-negative integer d. For example:

>               dec2hex (2748)
>                    ⇒ "ABC"

> If d is a vector, return a string matrix, one row per value, padded with leading zeros to the width of the largest value.

> The optional second argument, len, specifies the minimum number of digits in the result.

> See also: hex2dec, dec2base, dec2bin.

— Function File: hex2dec (s)

> Return the integer corresponding to the hexadecimal number represented by the string s. For example:

>               hex2dec ("12B")
>                    ⇒ 299
>               hex2dec ("12b")
>                    ⇒ 299

> If s is a string matrix, returns a column vector of converted numbers, one per row of s. Invalid rows evaluate to NaN.

> See also: dec2hex, base2dec, bin2dec.

— Function File: dec2base (d, base)
— Function File: dec2base (d, base, len)

> Return a string of symbols in base base corresponding to the non-negative integer d.

>               dec2base (123, 3)
>                    ⇒ "11120"

> If d is a vector, return a string matrix with one row per value, padded with leading zeros to the width of the largest value.

> If base is a string then the characters of base are used as the symbols for the digits of d. Space (' ') may not be used as a symbol.

>               dec2base (123, "aei")
>                    ⇒ "eeeia"

> The optional third argument, len, specifies the minimum number of digits in the result.

> See also: base2dec, dec2bin, dec2hex.

— Function File: base2dec (s, base)

> Convert s from a string of digits in base base to a decimal integer (base 10).

>               base2dec ("11120", 3)
>                    ⇒ 123

> If s is a matrix, returns a column vector with one value per row of s. If a row contains invalid symbols then the corresponding value will be NaN. Rows are right-justified before converting so that trailing spaces are ignored.

> If base is a string, the characters of base are used as the symbols for the digits of s. Space (' ') may not be used as a symbol.

>               base2dec ("yyyzx", "xyz")
>                    ⇒ 123

> See also: dec2base, bin2dec, hex2dec.

— Loadable Function: s = num2hex (n)

> Typecast a double precision number or vector to a 16 character hexadecimal string of the IEEE 754 representation of the number. For example:

>               num2hex ([-1, 1, e, Inf, NaN, NA]);
>               ⇒ "bff0000000000000
>                   3ff0000000000000
>                   4005bf0a8b145769
>                   7ff0000000000000
>                   fff8000000000000
>                   7ff00000000007a2"

> See also: hex2num, hex2dec, dec2hex.

— Loadable Function: n = hex2num (s)

> Typecast the 16 character hexadecimal character string to an IEEE 754 double precision number. If fewer than 16 characters are given the strings are right padded with '0' characters.

> Given a string matrix, `hex2num` treats each row as a separate number.

>               hex2num (["4005bf0a8b145769";"4024000000000000"])
>               ⇒ [2.7183; 10.000]

> See also: num2hex, hex2dec, dec2hex.

— Built-in Function: str2double (s)

> Convert a string to a real or complex number.

> The string must be in one of the following formats where a and b are real numbers and the complex unit is 'i' or 'j':

> - a + bi
> - a + b*i
> - a + i*b
> - bi + a
> - b*i + a
> - i*b + a

> If present, a and/or b are of the form [+-]d[,.]d[[eE][+-]d] where the brackets indicate optional arguments and 'd' indicates zero or more digits. The special input values `Inf`, `NaN`, and `NA` are also accepted.

> s may also be a character matrix, in which case the conversion is repeated for each row. Or s may be a cell array of strings, in which case each element is converted and an array of the same dimensions is returned.

> `str2double` returns NaN for elements of s which cannot be converted.

> `str2double` can replace `str2num`, and it avoids the security risk of using `eval` on unknown data.

> See also: str2num.

— Function File: strjust (s, pos)

> Return the text, s, justified according to pos, which may be ‘`"left"`’, ‘`"center"`’, or ‘`"right"`’. If pos is omitted, ‘`"right"`’ is assumed.

> Null characters are replaced by spaces. All other character data are treated as non-white space.

> Example:

>               strjust (["a"; "ab"; "abc"; "abcd"])
>                    ⇒ ans =
>                          a
>                         ab
>                        abc
>                       abcd

> See also: deblank, strrep, strtrim, untabify.

— Function File: str2num (s)

> Convert the string (or character array) s to a number (or an array). Examples:

>               str2num("3.141596")
>                    ⇒ 3.141596

>               str2num(["1, 2, 3"; "4, 5, 6"]);
>                    ⇒ ans =
>                       1  2  3
>                       4  5  6

> Caution: As `str2num` uses the `eval` function to do the conversion, `str2num` will execute any code contained in the string s. Use `str2double` instead if you want to avoid the use of `eval`.

> See also: str2double, eval.

— Mapping Function: toascii (s)

> Return ASCII representation of s in a matrix. For example:

>               toascii ("ASCII")
>                    ⇒ [ 65, 83, 67, 73, 73 ]

> See also: char.

— Mapping Function: tolower (s)
— Mapping Function: lower (s)

> Return a copy of the string or cell string s, with each uppercase character replaced by the corresponding lowercase one; non-alphabetic characters are left unchanged. For example:

>               tolower ("MiXeD cAsE 123")
>                    ⇒ "mixed case 123"

> See also: toupper.

— Mapping Function: toupper (s)
— Mapping Function: upper (s)

> Return a copy of the string or cell string s, with each lowercase character replaced by the corresponding uppercase one; non-alphabetic characters are left unchanged. For example:

>               toupper ("MiXeD cAsE 123")
>                    ⇒ "MIXED CASE 123"

> See also: tolower.

— Built-in Function: do_string_escapes (string)

> Convert special characters in string to their escaped forms.

— Built-in Function: undo_string_escapes (s)

> Convert special characters in strings back to their escaped forms. For example, the expression

>               bell = "\a";

> assigns the value of the alert character (control-g, ASCII code 7) to the string variable `bell`. If this string is printed, the system will ring the terminal bell (if it is possible). This is normally the desired outcome. However, sometimes it is useful to be able to print the original representation of the string, with the special characters replaced by their escape sequences. For example,

>               octave:13> undo_string_escapes (bell)
>               ans = \a

> replaces the unprintable alert character with its printable representation.