How to Reverse iterate an array in c ?-CodePudding

I am trying to reverse iterate an array of strings. The code below is working perfectly

QStringList aCodes;
aCodes<<"1"<<"2"<<"3"<<"4";
QStringList::iterator its;
for(its = aCodes.end()-1;its != aCodes.begin()-1;--its)
{
    qDebug()<<*its;
}

The code below is also working, but its is printing the last three strings only.

for(its = aCodes.end()-1;its != aCodes.begin();--its)
{
    qDebug()<<*its;
}

CodePudding user response：

QStringList inherits QList which provides STL-like iterators, meaning it supports reverse_iterator.

QStringList::reverse_iterator its;
for(its = aCodes.rbegin(); its != aCodes.rend();   its)
{
    qDebug() << *its;
}

CodePudding user response：

You can avoid a raw for loop altogether with std::for_each if you #include <algorithm>:

#include <algorithm>
std::for_each(std::rbegin(aCodes), std::rend(aCodes), [&](auto &ac) { qDebug() << ac; }

For more info, see cppreference on reverse iterators.