I thought one could declare several variables in a for
loop:
for (int i = 0, char* ptr = bam; i < 10; i++) { ... }
But I just found out that this is not possible. GCC gives the following error:
error: expected unqualified-id before 'char'
Is it really true that you can't declare variables of different types in a for
loop?
You can (but generally shouldn't) use a local struct type.
for ( struct { int i; char* ptr; } loopy = { 0, bam };
loopy.i < 10 && * loopy.ptr != 0;
++ loopy.i, ++ loopy.ptr )
{ ... }
Since C++11, you can initialize the individual parts more elegantly, as long as they don't depend on a local variable:
for ( struct { int i = 0; std::string status; } loop;
loop.status != "done"; ++ loop.i )
{ ... }
This is just almost readable enough to really use.
C++17 addresses the problem with structured bindings:
using namespace std::literals::string_literals;
for ( auto [ i, status ] = std::tuple{ 0, ""s }; status != "done"; ++ i )