c - 将文件中的数字读入二维矩阵

Question

我正在尝试编写一个函数来将文件中的数字读取到二维矩阵中； mm_alloc() 函数是一个创建空矩阵的函数，并且该文件的第一行是矩阵的大小；但代码似乎无法从文件中读取，我的问题是什么？我是否错误地使用了 fgets() 和 sscanf()？

double **mm_alloc( int size )
{
    double **matrix;
    int i;
    matrix = (double **)malloc((size) * sizeof(double *));
    for ( i = 0; i < size; i++ ) {
        matrix[i] = (double *)malloc(size);
    }
    return( matrix );
}


double **mm_read( char *filename, int *size ) 
{
    FILE *myfile;
    myfile = fopen(filename, "r");
    char read[256];
    fgets(read, 256, myfile);
    sscanf(read, "%d", size);
    int i, j;
    double **Matrix;
    Matrix = mm_alloc( *size );
    for ( i = 0; i < *size; i++ ) {
        for ( j = 0; j < *size; j++) {
            fgets(read, 256, myfile);
            sscanf(read, "%lf", &Matrix[i][j]);
        }
    }
    fclose (myfile);
    return( Matrix );
}

void mm_free( int size, double **matrix  )
{
    int i;
    for ( i = 0; i < size; i++ ) {
        free(matrix[i]);
    }
    free(matrix);
}

void mm_print( int size, double **matrix )
{
    int i, j;
    for ( i = 0; i < size; i++ ) {
        for ( j = 0; j < size; j++ ) {
            printf("%16f", matrix[i][j]);
        }
        printf("\n");
    }
}

double **mm_swap( int size, double **matrix ) 
{
    double **swap;
    swap = mm_alloc(size);
    int i, j;
    for ( i = 0; i < size; i++ ) {
        for ( j = 0; j < (size-2); j++) {
            swap[i][j] = matrix[i][j+2];
            swap[i][j+2] = matrix[i][j];
        }
    }
    return( swap );
}

double **mm_matrix_mult( int size, double **matrix, double **transpose )
{
    double **matrix_mult;
    matrix_mult = mm_alloc(size);
    int i, j, k;
    double result;
    for ( i = 0; i < size; i++ ) {
        for ( j = 0; j < size; j++ ) {
            result = 0;
            for ( k = 0; k < size; k++ ) {
                result += (matrix[i][k] * transpose[k][j]);
            }
            matrix_mult[i][j] = result;
        }
    }
    return( matrix_mult );
}

int main()
{
    char filename[256];
    double **matrix=NULL;
    double **swap_matrix=NULL;
    double **results_matrix=NULL;
    int size=0;

    printf("Please enter the matrix data file name: ");
    scanf( "%s", filename );

    matrix = mm_read( filename, &size );
    swap_matrix = mm_swap( size, matrix ); 
    results_matrix = mm_matrix_mult( size, matrix, swap_matrix );

    mm_print( size, results_matrix );
    mm_free( size, matrix );
    mm_free( size, swap_matrix );
    mm_free( size, results_matrix );
    return( 0 ); 
}

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Answer 1

您正在使用“w”打开文件。

这将删除该文件。您需要使用“r”打开才能读取文件。