Well, the API for Integer.valueOf(String) does indeed say that the String is interpreted exactly as if it were given to Integer.parseInt(String). However, valueOf(String) returns a new Integer() object whereas parseInt(String) returns a primitive int. If you want to enjoy the potential caching benefits of Integer.valueOf(int), you could also use this eyesore: Integer k = Integer.valueOf(Integer.parseInt(“123”)) … Read more
You can use the strval() function to convert a number to a string. From a maintenance perspective its obvious what you are trying to do rather than some of the other more esoteric answers. Of course, it depends on your context. $var = 5; // Inline variable parsing echo “I’d like {$var} waffles”; // = … Read more
with positive integers you could use .isdigit: >>> ’16’.isdigit() True it doesn’t work with negative integers though. suppose you could try the following: >>> s=”-17″ >>> s.startswith(‘-‘) and s[1:].isdigit() True it won’t work with ‘16.0’ format, which is similar to int casting in this sense. edit: def check_int(s): if s[0] in (‘-‘, ‘+’): return s[1:].isdigit() … Read more
In C++11 there are some nice new convert functions from std::string to a number type. So instead of atoi( str.c_str() ) you can use std::stoi( str ) where str is your number as std::string. There are version for all flavours of numbers: long stol(string), float stof(string), double stod(string),… see http://en.cppreference.com/w/cpp/string/basic_string/stol
The math.ceil (ceiling) function returns the smallest integer higher or equal to x. For Python 3: import math print(math.ceil(4.2)) For Python 2: import math print(int(math.ceil(4.2)))
In alphabetical order: std::string name = “John”; int age = 21; std::string result; // 1. with Boost result = name + boost::lexical_cast<std::string>(age); // 2. with C++11 result = name + std::to_string(age); // 3. with FastFormat.Format fastformat::fmt(result, “{0}{1}”, name, age); // 4. with FastFormat.Write fastformat::write(result, name, age); // 5. with the {fmt} library result = fmt::format(“{}{}”, … Read more
Given: xs = [‘1’, ‘2’, ‘3’] Use map then list to obtain a list of integers: list(map(int, xs)) In Python 2, list was unnecessary since map returned a list: map(int, xs)
In Python 2, division of two ints produces an int. In Python 3, it produces a float. We can get the new behaviour by importing from __future__. >>> from __future__ import division >>> a = 4 >>> b = 6 >>> c = a / b >>> c 0.66666666666666663
You didn’t say what kind of language they expected… Here’s a static solution (Haskell). It’s basically messing with the 2 most significant bits: f :: Int -> Int f x | (testBit x 30 /= testBit x 31) = negate $ complementBit x 30 | otherwise = complementBit x 30 It’s much easier in a … Read more
If you need to do this, do isinstance(<var>, int) unless you are in Python 2.x in which case you want isinstance(<var>, (int, long)) Do not use type. It is almost never the right answer in Python, since it blocks all the flexibility of polymorphism. For instance, if you subclass int, your new class should register … Read more