How to resolve the algorithm Gotchas step by step in the J programming language

Published on 12 May 2024 09:40 PM
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How to resolve the algorithm Gotchas step by step in the J programming language

Table of Contents

Problem Statement

In programming, a gotcha is a valid construct in a system, program or programming language that works as documented but is counter-intuitive and almost invites mistakes because it is both easy to invoke and unexpected or unreasonable in its outcome. Give an example or examples of common gotchas in your programming language and what, if anything, can be done to defend against it or them without using special tools.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Gotchas step by step in the J programming language

Source code in the j programming language

   ex1=: 1 2 3 4 5
   ex2=: '1 2 3 4 5'
   ex1
1 2 3 4 5
   ex2
1 2 3 4 5
   10+ex1
11 12 13 14 15
   10+ex2
|domain error


   1 2 3 + 4 5 6
5 7 9
   +/ 1 2 3 + 4 5 6
21
   1 2 3 +/@:+ 4 5 6
21
   1 2 3 +/@+ 4 5 6
5 7 9


   10 100 1000 +/ .*1 2 3  NB. vector multiplication
3210
   10 100 1000 +/.*1 2 3   NB. complex conjugate of signum of right argument grouped by the left argument
1
1
1


   A=: 2 3 5 7 11    NB. legal
   B=: 999           NB. legal
   B 0} A            NB. functional array update (does not change A)
   NB. the use of a single brace to denote indexing might also confuse people
999 3 5 7 11
   0} A              NB. legal
2
   999 0} A          NB. not legal
|rank error
   (999)0} A         NB. what was intended
999 3 5 7 11


   0x100   NB. 0*e^100 where e is the natural logarithm base 2.71828...
0
   0xff
|ill-formed number
   16b100 16bff
256 255
   8ad90   NB. 8 on the complex plane at an angle of 90 degrees from the real axis
0j8 
   -100   NB. two tokens
_100
   _100+10   NB. three tokens
_90
   -100+10   NB. four tokens
_110


   1+2*3   NB. processed right-to-left
7
   2*3+1   NB. processed right-to-left
8

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