程序检查2D数组中是否存在任何数字

本文介绍了程序检查2D数组中是否存在任何数字的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我知道如何检查数组中是否存在数字，但 2D数组中不存在。

I know how to check if number exist in the array, but not in a 2D array.

请以二维帮助我。

#include<iostream> using namespace std; int main() { int a[3] = { 4,5,6 }; int b, c; int x = 1, fact = 1; cout << "enter no "; cin >> b; for (int i = 0; i < 3; i++) { if (b == a[i]) { c = a[i]; break; } } cout << "no entered is present" << endl; }

推荐答案

我知道如何检查数组中是否存在数字，但不检查2D数组中是否存在数字！

I know how to check if number exist in the array, but not in 2D array!

就像您对一维数组所做的一样，而不是一个，您现在需要遍历行和列。换句话说，您需要再进行一次迭代。

It is like you did for the one-dimensional array, instead of one, you need to now iterate through the rows and column. In another word, you need one more iteration.

#include<iostream> int main() { int a[2][3]{ { 1,2,3 }, { 4,5,6 } }; int userInput = 5; bool found = false; for (int row = 0; !found && row < 2; ++row) // if not found and row size < 2 { for (int col = 0; col < 3; ++col) // if column size < 3 { if (userInput == a[row][col]) // access the element like this { // other codes std::cout << "No entered is present\n"; found = true; break; } } } }

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但是，我不建议这样使用行大小和列大小。您应该使用更好的 std :: array （如果您在编译时知道大小），或者 std :: vector （如果在运行时知道大小）。

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However, using the row size and column size like this, I will not recommend so. You should be using better std::array(if you know the size at compile time), or std::vector(if the sizes are known at run time).

例如，使用 std :: array ，您可以使用以下代码（示例代码）。使用 基于范围的

For example, using std::array you could have the following code(example code). Using the range based for-loop, and a simple function makes the code more readable and less error-prone. Also, you need to know the sizes known at compile time. (See live demo)

#include <iostream> #include <array> // std::array bool isIn2DArray(const std::array<std::array<int, 3>, 2>& arr, int val) /* noexcept */ { // range based for-loop instead of index based looping for (const std::array<int, 3> & row : arr) for (const int element : row) if (element == val) return true; // if found in the array, just return the boolean! return false; // if not found! } int main() { std::array<std::array<int, 3>, 2> a{ { { 1,2,3 }, { 4,5,6 } } }; int userInput = 5; if (isIn2DArray(a, userInput)) // you call the function like this! { std::cout << "Found in the array!\n"; } else { std::cout << "Didn't find!\n"; } }

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如果想知道，如何为任意数组提供 isIn2DArray ，方法是提供大小为非模板参数，如下所示。 （观看实时演示）

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In case of wondering, how to provide isIn2DArray for any arbitrary array, do it by providing the sizes as non-template parameters as below. (See live demo)

#include <array> // std::array template<std::size_t Row, std::size_t Col> bool isIn2DArray(const std::array<std::array<int, Col>, Row>& arr, int val)/* noexcept */ { // range based for-loop instead of index based looping for (const std::array<int, 3> & row : arr) for (const int element : row) if (element == val) return true; // if found in the array, just return the boolean! return false; // if not found! }