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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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