25.5.3  Converting strings to giac expressions

Using strings as commands.

The expr command lets you use a string as a command.

• expr takes str, a string which expresses a valid command.
• expr(str) converts str to the command and evaluates it.

Examples

which is the same thing as entering ifactor(54) directly.

Converting strings to numbers.

You can also use expr to convert a string to a number. If a string is simply a number enclosed by quotation marks, then expr will return the number.

Examples

The following strings will be converted to the appropriate number.

A string consisting of the digits 0-9 which does not start with 0 will be converted to an integer:

A string consisting of the digits 0-9 that contains a single decimal point will be converted to a double:

A string consisting of the digits 0-9 and a single decimal point, followed by e and then more digits, will be read as a floating point number:

A string consisting of the digits 0-7 which starts with 0 will be read as an integer base 8:

since 176 base 8 equals 126 base 10.

A string starting with 0x followed by digits 0-9 and letters A-F (or a-f) will be read as an integer base 16:

since 2A3F base 16 equals 10815 base 10.

A string starting with 0b followed by digits 0 and 1 will be read as a binary integer:

since 1101 base 2 equals 13 base 10.