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Convert from std::vector

Convert from std::vector

作者: 未来已来_1cab | 来源:发表于2019-04-26 17:30 被阅读0次

There is a function which takes a float** parameter. I have the values in a variable of type std::vector<std::vector<float>>.
Is it possible to make such a conversion without allocating a temporary float*[] ?

#include <vector>
#include <iostream>
#include <stdlib.h>
#include <time.h>

using namespace std;

void compare(int m, int n, float **score)
{
    for(int i=0; i<m; i++)
    {
        for(int j=0; j<n; j++)
        {
            score[i][j] = (i*n + j)/100.0;
        }
    }
}

int main()
{
    int m=20, n=5;

    vector<float> vec1(n);
    vector<vector<float>> vec2;
    for(int i=0; i<m; i++)
    {
        vec2.push_back(vec1);
    }

    vector<float*> target(vec2.size());
    for (int i = 0; i < vec2.size(); ++i)
    {
        target[i] = &*vec2[i].begin();
    }
    compare(m, n, target.data());

    for(int i=0; i<m; i++)
    {
        for(int j=0; j<n; j++)
        {
            cout << vec2[i][j] << "\t";
        }
        cout << endl;
    }
    
    return 0;
}

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