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| Jorgen Grahn <grahn+nntp@snipabacken.se>: Apr 29 07:34PM > How to write program to find bonus? I'm beginner to learn c++. > I have working hours and bonus but i can't write code? How i do? If you're reading this: I think your problem is about understanding the problem: translating it from text to mathematics. C++ programmers cannot help you with that part. When you've gotten so far that you can express it as code (in C++, some other language, or pseudocode) someone can help you with any C++-specific problems. /Jorgen -- // Jorgen Grahn <grahn@ Oo o. . . \X/ snipabacken.se> O o . |
| Thiago Adams <thiago.adams@gmail.com>: Apr 29 10:03AM -0700 Let's say you want to create a switch case for strings. switch (key) { case "Sunday": break; case "Monday":break; case "Tuesday": break; case "Wednesday": break; case "Thursday": break; case "Friday: break; case "Saturday": break; } I created an simple online generator for this. http://thradams.com/switchgenerator.html For instance (given a list of string): Input: Sunday Monday Tuesday Wednesday Thursday Friday Saturday Output: int find(const char* key) { int result = -1; switch (key[0]) { case /*Friday*/ 'F' : if (key[1]=='r' && key[2]=='i' && key[3]=='d' && key[4]=='a' && key[5]=='y' && key[6]=='\0') { result = 0; } break; case /*Monday*/ 'M' : if (key[1]=='o' && key[2]=='n' && key[3]=='d' && key[4]=='a' && key[5]=='y' && key[6]=='\0') { result = 1; } break; case 'S': switch (key[1]) { case /*Saturday*/ 'a' : if (key[2]=='t' && key[3]=='u' && key[4]=='r' && key[5]=='d' && key[6]=='a' && key[7]=='y' && key[8]=='\0') { result = 2; } break; case /*Sunday*/ 'u' : if (key[2]=='n' && key[3]=='d' && key[4]=='a' && key[5]=='y' && key[6]=='\0') { result = 3; } break; default : break; } break; case 'T': switch (key[1]) { case /*Thursday*/ 'h' : if (key[2]=='u' && key[3]=='r' && key[4]=='s' && key[5]=='d' && key[6]=='a' && key[7]=='y' && key[8]=='\0') { result = 4; } break; case /*Tuesday*/ 'u' : if (key[2]=='e' && key[3]=='s' && key[4]=='d' && key[5]=='a' && key[6]=='y' && key[7]=='\0') { result = 5; } break; default : break; } break; case /*Wednesday*/ 'W' : if (key[1]=='e' && key[2]=='d' && key[3]=='n' && key[4]=='e' && key[5]=='s' && key[6]=='d' && key[7]=='a' && key[8]=='y' && key[9]=='\0') { result = 6; } break; default : break; } return result; } |
| Bonita Montero <Bonita.Montero@gmail.com>: Apr 29 07:08PM +0200 Better use a unordered_map to a scalar value on which you do a switch. |
| Thiago Adams <thiago.adams@gmail.com>: Apr 29 10:13AM -0700 On Monday, April 29, 2019 at 2:08:10 PM UTC-3, Bonita Montero wrote: > Better use a unordered_map to a scalar value on which you do a switch. Why do you think unordered_map is better? |
| Christian Gollwitzer <auriocus@gmx.de>: Apr 29 07:18PM +0200 Am 29.04.19 um 19:03 schrieb Thiago Adams: > For instance (given a list of string): > Input: > Sunday Monday Tuesday Wednesday Thursday Friday Saturday A classic tool for this task is the "perfect hash", gperf is one of the tools. If I feed it with the same string, it outputs the code below. A perfect hash tries to compute the correct answer in a small number of arithmetic operations, which can be lead to very fast lookups. In cases where performance does not matter, I'd prefer a simple linear scan. So: std::string input = "Monday"; std::vector<std::string> wdays {"Sunday", "Monday", "tuesday", ...}; auto day = std::find(std::begin(input), std::end(input), wdays); or perhaps using a std::map. Or a chain of if/else blocks, which can be simplified using the preprocessor: #define OPTION(X) else if (input == #X) if (false) { // NOP } OPTION(Sunday) { // do this } OPTION(Monday) { // do that } ... #undef OPTION Christian ============ code by gperf ==================================== /* C code produced by gperf version 3.0.3 */ /* Command-line: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/gperf */ /* Computed positions: -k'1' */ #if !((' ' == 32) && ('!' == 33) && ('"' == 34) && ('#' == 35) \ && ('%' == 37) && ('&' == 38) && ('\'' == 39) && ('(' == 40) \ && (')' == 41) && ('*' == 42) && ('+' == 43) && (',' == 44) \ && ('-' == 45) && ('.' == 46) && ('/' == 47) && ('0' == 48) \ && ('1' == 49) && ('2' == 50) && ('3' == 51) && ('4' == 52) \ && ('5' == 53) && ('6' == 54) && ('7' == 55) && ('8' == 56) \ && ('9' == 57) && (':' == 58) && (';' == 59) && ('<' == 60) \ && ('=' == 61) && ('>' == 62) && ('?' == 63) && ('A' == 65) \ && ('B' == 66) && ('C' == 67) && ('D' == 68) && ('E' == 69) \ && ('F' == 70) && ('G' == 71) && ('H' == 72) && ('I' == 73) \ && ('J' == 74) && ('K' == 75) && ('L' == 76) && ('M' == 77) \ && ('N' == 78) && ('O' == 79) && ('P' == 80) && ('Q' == 81) \ && ('R' == 82) && ('S' == 83) && ('T' == 84) && ('U' == 85) \ && ('V' == 86) && ('W' == 87) && ('X' == 88) && ('Y' == 89) \ && ('Z' == 90) && ('[' == 91) && ('\\' == 92) && (']' == 93) \ && ('^' == 94) && ('_' == 95) && ('a' == 97) && ('b' == 98) \ && ('c' == 99) && ('d' == 100) && ('e' == 101) && ('f' == 102) \ && ('g' == 103) && ('h' == 104) && ('i' == 105) && ('j' == 106) \ && ('k' == 107) && ('l' == 108) && ('m' == 109) && ('n' == 110) \ && ('o' == 111) && ('p' == 112) && ('q' == 113) && ('r' == 114) \ && ('s' == 115) && ('t' == 116) && ('u' == 117) && ('v' == 118) \ && ('w' == 119) && ('x' == 120) && ('y' == 121) && ('z' == 122) \ && ('{' == 123) && ('|' == 124) && ('}' == 125) && ('~' == 126)) /* The character set is not based on ISO-646. */ error "gperf generated tables don't work with this execution character set. Please report a bug to <bug-gnu-gperf@gnu.org>." 
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