implement add with + operator with racket

 #lang racket

; implement add without + operator

(define add

  (λ (n m)

    (cond

      ((zero? m) n)

      (else (add1

            (add n (sub1

                    m)))))))

One thing I want to notice is that add1 and sub1 are not what I defined myself.

racket basic

 #lang racket

; define a constant

(define myval 3.14)

; function without param

(define myfunc

  (λ ()

    (+ 3 4)))

; call function

(myfunc)

; function with param(which is one formal)

(define myfunc-mul-two

  (λ (x)

    (* 2 x)))

(myfunc-mul-two 4)

; outer function calls inner function

(define double-result-of-f

  (λ (f)

    (λ (z)

      (* 2 (f z)))))

(define add3

  (λ (x)

    (+ 3 x)))

((double-result-of-f add3) 4)

binary search alternative

#include <iostream>

#include <vector>

using namespace std;

int main()

{

    int array[] = { 1,3,3,4,5,5,6,9,10,12,12,15 };

    int n = sizeof(array) / sizeof(int);

    int k = 0;

    int x = 3;

    for (int b = n / 2; b >= 1; b /= 2)

    {

        while (k + b < n && array[k + b] <= x)

        {

            k += b;

        }

    }

    

    if (array[k] == x)

    {

        int a = 10;

    }

}

remainder in racket

 #lang racket

(define remainder

  (λ (x y)

    (cond

      ((< x y) x)

      (else (remainder (- x y) y)))))

unix tree

minnie.tuhs.org/cgi-bin/utree.pl

which on linux

which is used to locate a command. which returns the pathnames of the files (or links) which would be executed in the current environment, had its arguments been given as commands in a strictly POSIX-conformant shell. It does this by searching the PATH for executable files matching the names of the arguments. It does not follow symbolic links.

unreal engine gpu profiling commands

stat gpu

stat rhi

stat unit

ProfileGPU

stdc++

#include <bits/stdc++.h>

using namespace std;

int main()

{

}

stdc++.h allows us to include the entire standard library so I don't need to include each separate header files such as vector, iostream, algorithm and so on.

but it is only for competitive programming not for a professional developer.

use gdbm on ubuntu

First thing you have to do is checking whether gdbm is installed on your system or not.

normally it is installed on /usr/include

find /usr/include *dbm* is the command you can use.

even though gdbm is installed on your machine, you might need to install gdbm_compat if you use ndbm interface.

sudo apt-get install apt-file

apt-file update

apt-file search ndbm.h

then you will see packages that you should install on your machine.

안다는 것

子曰 由, 誨女知之乎. 知之爲知之, 不之爲不知, 是知也

List symbols from object file on linux

 

search all of the symbols in a program. if you can see any of functions beginning of aio_ then for sure it uses async I/O.