如何获取数组中已用空间的大小？(How to get the size of the used space in an array? (NOT sizeof); c++)

如何获取数组中已用空间的大小？(How to get the size of the used space in an array? (NOT sizeof); c++) #include<iostream> using namespace std; int main() { char arr[200]; while(1) { cin >> arr; int i = sizeof(arr); cout << "The arr input is "<< arr << " and the size of the array is "<< i << endl; } return 0; }

对于34的输入，此代码输出：arr输入为34，数组大小为200

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而我希望它获得数组使用空间的大小。 所以对于我希望它输出的最后一个输入：arr输入是34，数组的大小是2

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有人能告诉我怎么样？

#include<iostream> using namespace std; int main() { char arr[200]; while(1) { cin >> arr; int i = sizeof(arr); cout << "The arr input is "<< arr << " and the size of the array is "<< i << endl; } return 0; }

For the input of 34, This code outputs :The arr input is 34 and the size of the array is 200

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while I want it to get the size of the used space of the array . So for The last input i want it to output :The arr input is 34 and the size of the array is 2

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Can someone tell me how?

最满意答案

也许你想在这里使用strlen(arr) 。 它必须以null结尾，否则cout << arr将无效。

你需要#include <cstring>

Maybe you want strlen(arr) here. It must be null terminated, otherwise the cout << arr would not have worked.

You would need to #include <cstring>