使用 foreach 语法进行迭代时如何检查我是否在最后一个元素上

2021-12-26 00:00:00 foreach c++ c++11

例如:

for( auto &iter: item_vector ) {
     if(not_on_the_last_element) printf(", ");
}

或

for( auto &iter: skill_level_map ) {
     if(not_on_the_last_element) printf(", ");
}

推荐答案

你真的不能.这就是 range-for 的意义所在，即您不需要迭代器.但是，如果不是第一个，您可以更改关于如何打印逗号的逻辑来打印它:

You can't really. That's kind of the point of range-for, is that you don't need iterators. But you can just change your logic on how you print your comma to print it if it's not first:

bool first = true;
for (auto& elem : item_vector) {
    if (!first) printf(", ");
    // print elem
    first = false;
}

如果这就是循环的意图.或者您可以比较地址:

If that's the intent of the loop anyway. Or you could compare the addresses:

for (auto& elem : item_vector) {
    if (&elem != &item_vector.back()) printf(", ");
    // ...
}

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