Question

Why does this C++ code not compile under VS2010:

for ( int a = 0, short b = 0; a < 10; ++a, ++b ) {}

while this one does:

short b = 0;
for ( int a = 0; a < 10; ++a, ++b ) {}

Is the declaration of two variables of different types inside the for-loop initializer prohibited? If so, how can you work around it?

Answer 1

Yes, that is prohibited. Just as otherwise you cannot declare variables of differing types in one declaration statement (edit: modulo the declarator modifiers that @MrLister mentions). You can declare structs

for (struct { int a = 0; short b = 0; } d; d.a < 10; ++d.a, ++d.b ) {}

C++03 code:

for (struct { int a; short b; } d = { 0, 0 }; d.a < 10; ++d.a, ++d.b ) {}

Of course when all are 0, you can omit the initializers altogether and write = { }.