C++ 二维数组打印出元素的总和
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2D array print out sum of elements
提问by user1582575
I writing a program that sum of elements in a 2D array and print out the sum.
我编写了一个程序，将二维数组中的元素相加并打印出总和。
Here my code so far:
到目前为止，我的代码是：
#include <iostream>
#include <stdio.h>
int main()
{
int array [3][5] =
{
{ 1, 2, 3, 4, 5, }, // row 0
{ 6, 7, 8, 9, 10, }, // row 1
{ 11, 12, 13, 14, 15 } // row 2
};
int i, j=0;
int num_elements=0;
float sum=0;
for (i=0; i<num_elements; i++)
{
sum = sum + array[i][j];
}
/*for(i=0; i<num_elements; i++)
{
printf("%d ", array[i][j]);
}*/
// printf("a[%d][%d] = %d\n", sum);
// output each array element's value
for ( i = 0; i < 3; i++ )
{
for ( j = 0; j < 5; j++ )
{
printf("a[%d][%d] = %d\n", i,j, array[i][j]);
}
}
system("PAUSE");
return 0;
}
I can print out the elements in each array fine. But I want to print out the sum of elements. I tried one as you can see in the comment section but it didn't work. Can anyone help?
我可以很好地打印出每个数组中的元素。但我想打印出元素的总和。正如您在评论部分看到的那样，我尝试了一个，但没有用。任何人都可以帮忙吗？
回答by Manos Ikonomakis
You are summing only the first column of your matrix:
您只对矩阵的第一列求和：
sum = sum + array[i][j];
where j is set to 0.
其中 j 设置为 0。
use a double loop:
使用双循环：
for ( i = 0; i < 3; i++ )
{
for ( j = 0; j < 5; j++ )
{
sum+=array[i][j];
}
}
回答by Chowlett
This loop's the problem:
这个循环的问题：
int i, j=0;
int num_elements=0;
float sum=0;
for (i=0; i<num_elements; i++)
{
sum = sum + array[i][j];
}
It won't execute at all, since i<num_elementsis never true - num_elementsis 0. On top of which, you don't ever set jaway from 0.
它根本不会执行，因为i<num_elements它永远不会是真的 -num_elements是 0。最重要的是，你永远不会j离开 0。
You need a double loop, like you use later on:
您需要一个双循环，就像您稍后使用的那样：
for ( i = 0; i < 3; i++ )
{
for ( j = 0; j < 5; j++ )
{
sum += array[i][j];
}
}
回答by Hashim Khan
Try this to sum of all elements in 2D array-
试试这个对二维数组中所有元素的总和 -
for ( i = 0; i < 3; i++ )
{
for ( j = 0; j < 5; j++ )
{
sum=sum+array[i][j];
}
}
回答by SoulRayder
First of all, you have initialized num_elements as zero. So you wont get anything.
首先，您已将 num_elements 初始化为零。所以你不会得到任何东西。
Also, for this,
另外，为此，
You need a double loop to print sum of allelements. Also declare additional variables such as row_num(for number of rows) and element_numfor number of elements in eachrow, and then use this code.
您需要一个双循环来打印所有元素的总和。还要声明额外的变量，例如row_num（用于行数）和element_num用于每行中的元素数，然后使用此代码。
for(i=0; i<row_num; i++)
{
for(j=0; j<element_num; j++)
{
sum = sum + array[i][j];
}
}
回答by Digital_Reality
As array stored in contiguous memory, it is possible to use only one loop.
由于数组存储在连续内存中，因此可以只使用一个循环。
for (int i=0; i<(3*5); i++) <-- 3*5 is num_of_colums*num_of_rows.
{
sum = sum + *(array[0]+i);
}
