如何在C ++中打印2D数组？ [英] How to print 2D Arrays in C++?

问题描述

我尝试使用数组在屏幕上打印文本文件，但我不知道为什么它不会出现在文本文件中。

文本文件：

  1 2 3 4 
 5 6 7 8 
  

在应用废弃函数后，在屏幕上显示如下：

  1 
 2 
 3 
 4 
 5 
 6 
 7 
 8 
  

代码：

  #include< iostream> 
 #include< fstream> 
 #include< stdlib.h> 
 #include< string> 
 
 using namespace std; 
 
 const int MAX_SIZE = 20; 
 const int TOTAL_AID = 4; 
 
 void discard_line（ifstream& in）; 
 void print（int print [] [4]，int size）; 
 
 int main（）
 {
 // string evnt_id [MAX_SIZE]; // stores event id 
 int athlete_id [MAX_SIZE] [TOTAL_AID]; //存储athelete id的列
 int total_records; 
 char c; 
 ifstream reg; 
 reg.open（C：\\result.txt）; 
 
 discard_line（reg）; 
 total_records = 0; 
 
 while（！reg.eof（））
 {
 for（int i = 0; i  {
 reg >> athlete_id [total_records] [i]; // read aid coloumns 
} 
 total_records ++; 
 reg.get（c）; 
} 
 
 reg.close（）; 
 
 print（athlete_id，total_records）; 
 
系统（pause）; 
 return 0; 
} 
 
 void discard_line（ifstream& in）
 {
 char c; 
 
 do 
 in.get（c）; 
 while（c！='\\\
'）; 
} 
 
 void print（int print [] [4]，int size）
 {
 cout< \tID \t AID< endl; 
 for（int i = 0; i  {
 for（int j = 0; j  {
 cout < print [i] [j]< endl; 
} 
} 
} 
  

解决方案>

您正在每个数字后面打印 std :: endl 。如果你想每行有一行，那么你应该在每行后面打印 std :: endl 。示例：

  #include< iostream& 
 
 int main（void）
 {
 int myArray [] [4] = {{1,2,3,4}，{5,6,7,8} }; 
 int width = 4，height = 2; 
 
 for（int i = 0; i  {
 for（int j = 0; j< width; ++ j）
 {
 std :: cout<< myArray [i] [j]< ''; 
} 
 std :: cout<< std :: endl; 
} 
} 
  

命名空间std; 在文件开头被认为是坏习惯，因为它导致一些用户定义的名称（类型，函数等）变得模糊。如果你想避免使用 std :: 穷尽前缀，在小范围内使用使用namespace std; 和其他文件不受影响。

I am trying to print a text file out on screen using arrays, but I'm not sure why it does not appear the way it is in the text file.

The text file:

1 2 3 4
5 6 7 8

Displayed on the screen as follows after applying discard function:

1
2
3
4
5
6
7
8

The code:

#include <iostream>
#include <fstream>
#include <stdlib.h>
#include <string>

using namespace std;

const int MAX_SIZE = 20;
const int TOTAL_AID = 4;

void discard_line(ifstream &in);
void print(int print[][4] , int size);

int main()
{
    //string evnt_id[MAX_SIZE]; //stores event id
    int athlete_id[MAX_SIZE][TOTAL_AID]; //stores columns for athelete id
    int total_records;
    char c; 
    ifstream reg;
    reg.open("C:\\result.txt");

    discard_line(reg);
    total_records = 0;

    while( !reg.eof() )
    {
        for (int i = 0; i < TOTAL_AID; i++)
        {
            reg >> athlete_id[total_records][i] ;//read aid coloumns
        }
        total_records++;
        reg.get(c);
    }

    reg.close();

    print(athlete_id, total_records);

    system("pause");
    return 0;
}

void discard_line(ifstream &in)
{
    char c;

    do
        in.get(c);
    while (c!='\n');
}

void print(int print[][4] , int size)
{    
    cout << " \tID \t AID " << endl;
    for (int i = 0; i < size; i++)
    {
        for (int j = 0; j < TOTAL_AID; j++)
        {
            cout << print[i][j] << endl;
        }           
    }
}    

解决方案

You are printing std::endl after each number. If you want to have 1 row per line, then you should print std::endl after each row. Example:

#include <iostream>

int main(void)
{
    int myArray[][4] = { {1,2,3,4}, {5,6,7,8} };
    int width = 4, height = 2;

    for (int i = 0; i < height; ++i)
    {
        for (int j = 0; j < width; ++j)
        {
            std::cout << myArray[i][j] << ' ';
        }
        std::cout << std::endl;
    }
}

Also note that writing using namespace std; at the beginning of your files is considered bad practice since it causes some of user-defined names (of types, functions, etc.) to become ambiguous. If you want to avoid exhausting prefixing with std::, use using namespace std; within small scopes so that other functions and other files are not affected.

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