向量迭代循环抛出错误? [英] vector iteration loop throwing an error?

问题描述

for (std::vector<int>::iterator it = v.begin(); it != v.end(); ++it)

错误:请求从'std :: vector :: const_iterator {aka __gnu_cxx :: __ normal_iterator>}'转换为非标量类型'std :: vector :: iterator {aka __gnu_cxx :: __ normal_iterator>}'

error: conversion from 'std::vector::const_iterator {aka __gnu_cxx::__normal_iterator >}' to non-scalar type 'std::vector::iterator {aka __gnu_cxx::__normal_iterator >}' requested

这是怎么回事?

推荐答案

您所处的环境是 v 是 const .改用 const_iterator .

You are in a context where v is const. Use const_iterator instead.

for (std::vector<int>::const_iterator it = v.begin(); it != v.end(); ++it)

注意1. auto 会自动为您执行此操作:

Note 1. auto would do this automatically for you:

for (auto it = v.begin(); it != v.end(); ++it)

注2.如果不需要访问迭代器本身，但需要访问容器的元素，则可以使用基于范围的循环:

Note 2. You could use a range based loop if you don't need access to the iterators themselves, but to the elements of the container:

for (auto elem : v) // elem is a copy. For reference, use auto& elem

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