问题描述
vector< vector<int> > resizeVector(vector< vector<int> > m)
{
vector< vector<int> > newMatrix;
int i,j;
for (i = 0; i < m[i].size(); i++)
{
for(j = 0; j < m[j].size(); j++)
{
newMatrix[i][j] = m[i][j];
}
}
return (newMatrix);
}
我正在制作一个可以进行大量矩阵操作的程序,这部分是崩溃,我不知道为什么。我把它缩小到一行:
I am making a program that will do a whole lot of matrix manipulation, and this section is crashing and I don't exactly know why. I have narrowed it down to the line:
newMatrix[i][j] = m[i][j];
它在这里崩溃,我不知道为什么。
It crashes right here, and I am not sure why.
推荐答案
除了@Saurav发布的内容之外, newMatrix
是空的,因此您不能将值分配给 newMatrix [i] [j]
。您可以通过初始化给定大小的向量来解决此问题:
In addition to what @Saurav posted, newMatrix
is empty so you cannot assign values to newMatrix[i][j]
. You can fix this by initializing the vectors with a given size:
vector< vector<int> > resizeVector(vector< vector<int> > m)
{
vector< vector<int> > newMatrix(m.size());
int i,j;
for (i = 0; i < m.size(); i++)
{
newMatrix[i].resize(m[i].size());
for(j = 0; j < m[i].size(); j++)
{
newMatrix[i][j] = m[i][j];
}
}
return (newMatrix);
}
在for循环之前,我们初始化 newMatrix
有
m.size()
其中有许多空向量(由于它们的默认构造函数,向量为空)。在外部for循环的每次迭代期间,我们确保 newMatrix
中的每个向量使用 resize
成员具有正确的大小
Before the for-loops we initialize newMatrix
to have m.size()
many empty vectors inside of it (the vectors are empty due to their default constructor). During each iteration of the outer for-loop we ensure that each vector within newMatrix
has the correct size using the resize
member function.
请注意,如果你想要一个矢量的副本,你可以简单地写:
Note that if you want a copy of a vector you can simply just write:
vector< vector<int> > newMatrix(m);
这篇关于矢量分配崩溃,不知道为什么的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!