连接 2 个矩阵

Question

我有一个动态分配的矩阵，我想创建另一个矩阵，它是第一个矩阵，但旁边有另一个副本。例如，我有矩阵:

1122

My new matrix will be:

1 1 1 12 2 2 2

How can I concatenate them? This is my code in C:

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>

int **create_matrix(int row, int col)
{
    int **matrix = malloc(sizeof (int*)*row);
    int i;
    for (i = 0; i < row; i++)
    {
        matrix[i] = malloc(sizeof (int)*col);
    }
    return matrix;
}

void matrix_input(int **matrix, int row, int col)
{
    int i, j;
    printf("enter the elements of the matrix:\n");
    for (i = 0; i < row; i++)
    {

        for (j = 0; j < col; j++)
        {
            scanf("%d", &matrix[i][j]);
        }
    }
}

int **extend_matrix(int **matrix, int row, int col)
{
    int k, j;
    int i;
    int **extend_matrix = malloc(sizeof (int*)*row);
    for (k = 0; k < row + row; k++)
    {
        extend_matrix[k] = malloc(sizeof (int)*col);
    }
    extend_matrix = matrix;
    extend_matrix = (int**) realloc(extend_matrix, (row + row) * sizeof (int*));
    extend_matrix[j] = matrix[j];
    for (i = 0; i < row; i++)
    {
        extend_matrix[k] = matrix[i];
    }
}

void print_matrix(int **matrix, int row, int col)
{
    int i, j;
    for (i = 0; i < row; i++)
    {
        for (j = 0; j < col; j++)
        {
            printf(" %d ", matrix[i][j]);
        }
        printf("\n");
    }

}

void print_extend_matrix(int **extend_matrix, int row, int col)
{
    int k, j;
    for (k = 0; k < row + row; k++)
    {
        for (j = 0; j < col; j++)
        {
            printf("%d", extend_matrix[k][j]);
        }
        printf("\n");
    }
}

int main(void)
{
    int **matrix;
    int **extend_matrix;
    int row, col;
    printf("enter the number of rows of cols:");
    scanf("%i%i", &row, &col);
    matrix = create_matrix(row, col);
    matrix_input(matrix, row, col);
    print_matrix(matrix, row, col);
    print_extend_matrix(extend_matrix, row, col);
    getch();
    return 0;
} 

Answer 1

尽管@NPE 向您建议了一个更好的方法。如果要在extend_matrix()中分配内存

代码错误(阅读评论)

int **extend_matrix = malloc(sizeof (int*)*row);
                                           ^ on row
for (k = 0; k < row + row; k++)            
                    ^ where as loop is for row + row
{
    extend_matrix[k] = malloc(sizeof (int)*col);  // So this cause an error,
                                                  // segment-fault
}

其次，你复制内存的概念是错误的:

 extend_matrix = matrix;  

在这一行中，您将 matrix 分配给 extend_matrix 这是错误的。您需要在此处循环将每个元素从 matrix[][] 复制到 extend_matrix[][]。 (但首先纠正你的内存分配代码)