Introduction to C++ Basics Array/One-dimensional array/Two-dimensional array/Definition form/The role of array name
Table of contents
1. One-dimensional array definition square form
2. One-dimensional array array name
1. Two-dimensional array definition method
2. Two-dimensional array array name
3. Two-dimensional array application case
1. Brief introduction
Organize some knowledge developed in C++, so that you can consult and use it in time when you encounter similar problems later.
This section introduces that an array, the so-called array, is a collection that stores data elements of the same type, including the functions and precautions of array/one-dimensional array/two-dimensional array/definition form/array name. If there are deficiencies, welcome to point out, or if you have a better method, please leave a message.
Array features:
- Each data element in the array is of the same data type
- Arrays are made up of contiguous memory locations
Two, one-dimensional array
1. One-dimensional array definition square form
Three definition forms of dimensional array definition:
- data type array name[array length];
- data type array name[array length] = {value1,value2...};
- Data type array name[ ] = {value1,value2...};
illustrate:
- The naming convention of the array name is consistent with the naming convention of the variable name, do not have the same name as the variable
- The subscript in the array is indexed from 0
code:
#include <iostream>
using namespace std;
int main() {
//定义方式1
//数据类型 数组名[元素个数];
int score[10];
//利用下标赋值
score[0] = 100;
score[1] = 99;
score[2] = 85;
//利用下标输出
cout << score[0] << endl;
cout << score[1] << endl;
cout << score[2] << endl;
//第二种定义方式
//数据类型 数组名[元素个数] = {值1，值2 ，值3 ...};
//如果{}内不足10个数据，剩余数据用0补全
int score2[10] = { 100, 90,80,70,60,50,40,30,20,10 };
//逐个输出
//cout << score2[0] << endl;
//cout << score2[1] << endl;
//一个一个输出太麻烦，因此可以利用循环进行输出
for (int i = 0; i < 10; i++)
{
cout << score2[i] << endl;
}
//定义方式3
//数据类型 数组名[] = {值1，值2 ，值3 ...};
int score3[] = { 100,90,80,70,60,50,40,30,20,10 };
for (int i = 0; i < 10; i++)
{
cout << score3[i] << endl;
}
system("pause");
return 0;
}
2. One-dimensional array array name
Use of 1D array names:
- Can count the length of the entire array in memory
- You can get the first address of the array in memory
illustrate:
- Note that the array name is a constant and cannot be assigned
- Print the array name directly, you can view the first address of the memory occupied by the array
- Perform sizeof on the array name to get the size of the memory space occupied by the entire array
code:
#include <iostream>
using namespace std;
int main() {
//数组名用途
//1、可以获取整个数组占用内存空间大小
int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
cout << "整个数组所占内存空间为： " << sizeof(arr) << endl;
cout << "每个元素所占内存空间为： " << sizeof(arr[0]) << endl;
cout << "数组的元素个数为： " << sizeof(arr) / sizeof(arr[0]) << endl;
//2、可以通过数组名获取到数组首地址
cout << "数组首地址为： " << (int)arr << endl;
cout << "数组中第一个元素地址为： " << (int)&arr[0] << endl;
cout << "数组中第二个元素地址为： " << (int)&arr[1] << endl;
//arr = 100; 错误，数组名是常量，因此不可以赋值
system("pause");
return 0;
}
Three, two-dimensional array
Two-dimensional array: It is to add one more dimension to the one-dimensional array.
1. Two-dimensional array definition method
Four ways to define a two-dimensional array:
- `Data type array name[row number][column number];`
- `Data type array name[row number][column number] = {{data1, data2}, {data3, data4}};`
- `Data type array name[row number][column number] = {data 1, data 2, data 3, data 4};`
- `Data type array name[ ][number of columns] = {data 1, data 2, data 3, data 4};`
illustrate:
- The above 4 definition methods, using the second one is more intuitive and improves the readability of the code
- When defining a two-dimensional array, if the data is initialized, the number of rows can be omitted
code:
#include <iostream>
using namespace std;
int main() {
//方式1
//数组类型 数组名 [行数][列数]
int arr[2][3];
arr[0][0] = 1;
arr[0][1] = 2;
arr[0][2] = 3;
arr[1][0] = 4;
arr[1][1] = 5;
arr[1][2] = 6;
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < 3; j++)
{
cout << arr[i][j] << " ";
}
cout << endl;
}
//方式2
//数据类型 数组名[行数][列数] = { {数据1，数据2 } ，{数据3，数据4 } };
int arr2[2][3] =
{
{1,2,3},
{4,5,6}
};
//方式3
//数据类型 数组名[行数][列数] = { 数据1，数据2 ,数据3，数据4 };
int arr3[2][3] = { 1,2,3,4,5,6 };
//方式4
//数据类型 数组名[][列数] = { 数据1，数据2 ,数据3，数据4 };
int arr4[][3] = { 1,2,3,4,5,6 };
system("pause");
return 0;
}
2. Two-dimensional array array name
Use of 1D array names:
- View the memory space occupied by a two-dimensional array
- Get the first address of the two-dimensional array
code:
#include <iostream>
using namespace std;
int main() {
//二维数组数组名
int arr[2][3] =
{
{1,2,3},
{4,5,6}
};
cout << "二维数组大小： " << sizeof(arr) << endl;
cout << "二维数组一行大小： " << sizeof(arr[0]) << endl;
cout << "二维数组元素大小： " << sizeof(arr[0][0]) << endl;
cout << "二维数组行数： " << sizeof(arr) / sizeof(arr[0]) << endl;
cout << "二维数组列数： " << sizeof(arr[0]) / sizeof(arr[0][0]) << endl;
//地址
cout << "二维数组首地址：" << arr << endl;
cout << "二维数组第一行地址：" << arr[0] << endl;
cout << "二维数组第二行地址：" << arr[1] << endl;
cout << "二维数组第一个元素地址：" << &arr[0][0] << endl;
cout << "二维数组第二个元素地址：" << &arr[0][1] << endl;
system("pause");
return 0;
}
3. Two-dimensional array application case
Description: There are three students (Zhang San, Li Si, Wang Wu), the scores in one test are as follows, please output the total scores of the three students respectively
| language | math | English | |
|---|---|---|---|
| Zhang San | 100 | 100 | 100 |
| Li Si | 90 | 50 | 100 |
| Wang Wu | 60 | 70 | 80 |
Code:
#include <iostream>
using namespace std;
int main() {
int scores[3][3] =
{
{100,100,100},
{90,50,100},
{60,70,80},
};
string names[3] = { "张三","李四","王五" };
for (int i = 0; i < 3; i++)
{
int sum = 0;
for (int j = 0; j < 3; j++)
{
sum += scores[i][j];
}
cout << names[i] << "同学总成绩为： " << sum << endl;
}
system("pause");
return 0;
}