Merge #20429: refactor: replace (sizeof(a)/sizeof(a[0])) with C++17 std::size

e829c9afbf75e930db6c3fe77a269b0af5e7a3ad refactor: replace sizeof(a)/sizeof(a[0]) by std::size (C++17) (Sebastian Falbesoner)
365539c84691d470b44d35df374d8c049f8c1192 refactor: init vectors via std::{begin,end} to avoid pointer arithmetic (Sebastian Falbesoner)
63d4ee1968144cc3d115f92baef95785abf813ac refactor: iterate arrays via C++11 range-based for loops if idx is not needed (Sebastian Falbesoner)

Pull request description:

  This refactoring PR picks up the idea of #19626 and replaces all occurences of `sizeof(x)/sizeof(x[0])` (or `sizeof(x)/sizeof(*x)`, respectively) with the now-available C++17 [`std::size`](https://en.cppreference.com/w/cpp/iterator/size)  (as [suggested by sipa](https://github.com/bitcoin/bitcoin/pull/19626#issuecomment-666487228)), making the macro `ARRAYLEN` obsolete.

  As preparation for this, two other changes are done to eliminate `sizeof(x)/sizeof(x[0])` usage:
  * all places where arrays are iterated via an index are changed to use C++11 range-based for loops If the index' only purpose is to access the array element (as [suggested by MarcoFalke](https://github.com/bitcoin/bitcoin/pull/19626#discussion_r463404541)).
  * `std::vector` initializations are done via `std::begin` and `std::end` rather than using pointer arithmetic to calculate the end (also [suggested by MarcoFalke](https://github.com/bitcoin/bitcoin/pull/20429#discussion_r567418821)).

ACKs for top commit:
  practicalswift:
    cr ACK e829c9afbf75e930db6c3fe77a269b0af5e7a3ad: patch looks correct
  fanquake:
    ACK e829c9afbf75e930db6c3fe77a269b0af5e7a3ad
  MarcoFalke:
    review ACK e829c9afbf75e930db6c3fe77a269b0af5e7a3ad 🌩

Tree-SHA512: b01d32c04b9e04d562b7717cae00a651ec9a718645047a90761be6959e0cc2adbd67494e058fe894641076711bb09c3b47a047d0275c736f0b2218e1ce0d193d

1 files changed, 2 insertions, 3 deletions

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 97280c0d16..4796045730 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -9,7 +9,6 @@
 #include <consensus/merkle.h>
 #include <hash.h> // for signet block challenge hash
 #include <util/system.h>
-#include <util/strencodings.h>
 #include <versionbitsinfo.h>
 
 #include <assert.h>
@@ -135,7 +134,7 @@ public:
 
         bech32_hrp = "bc";
 
-        vFixedSeeds = std::vector<SeedSpec6>(pnSeed6_main, pnSeed6_main + ARRAYLEN(pnSeed6_main));
+        vFixedSeeds = std::vector<SeedSpec6>(std::begin(pnSeed6_main), std::end(pnSeed6_main));
 
         fDefaultConsistencyChecks = false;
         fRequireStandard = true;
@@ -240,7 +239,7 @@ public:
 
         bech32_hrp = "tb";
 
-        vFixedSeeds = std::vector<SeedSpec6>(pnSeed6_test, pnSeed6_test + ARRAYLEN(pnSeed6_test));
+        vFixedSeeds = std::vector<SeedSpec6>(std::begin(pnSeed6_test), std::end(pnSeed6_test));
 
         fDefaultConsistencyChecks = false;
         fRequireStandard = false;