Replace all non-digit with blank: the remaining string contains only digits. Integer.parseInt(s.replaceAll(“[\\D]”, “”)) This will also remove non-digits inbetween digits, so “x1x1x” becomes 11. If you need to confirm that the string consists of a sequence of digits (at least one) possibly followed a letter, then use this: s.matches(“[\\d]+[A-Za-z]?”)
The -1 is because integers start at 0, but our counting starts at 1. So, 2^32-1 is the maximum value for a 32-bit unsigned integer (32 binary digits). 2^32 is the number of possible values. To simplify why, look at decimal. 10^2-1 is the maximum value of a 2-digit decimal number (99). Because our intuitive … Read more
In Postgresql int and int4 are aliases for integer, a signed four-byte integer http://www.postgresql.org/docs/current/static/datatype.html#DATATYPE-TABLE
negative or positive. Anything that’s not a 0 is a true value in if Also, Consider a negative number: -1 -1 in C internally is represented as: 0xFFFFFFFF, in which case, it would be a positive number if I cast it to unsigned integer. But after the advent of C99 standard compilers, I suggest you … Read more
Use the int function to get the integer part of the result, truncated toward 0. This produces the nearest integer to the result, located between the result and 0. For example, int(3/2) is 1, int(-3/2) is -1. Source: The AWK Manual – Numeric Functions
You mean this? num = 1234 lst = [int(i) for i in str(num)]
Don’t drop the column, use this change_column :table_name, :column_name, ‘integer USING CAST(column_name AS integer)’ The “hint” you got from PostgreSQL basically tells you that you need to confirm you want this to happen, and how data should be converted. To confirm the changes, use the block above in your migration
It’s normal behaviour of the language. Quoting the perlsyn manpage: The number 0, the strings ‘0’ and “”, the empty list (), and undef are all false in a boolean context. All other values are true. Negation of a true value by ! or not returns a special false value. When evaluated as a string … Read more