c - 释放动态分配的矩阵

Question

我有这段代码用于在运行时分配浮点矩阵:

float **create_matrix(int w, int h) {
    // alocates the matrix rows first
    float **matrix = (float**)malloc(h * sizeof(float*));

    // now allocates and populates each line
    for (int i = 0; i < h; i++) {
        matrix[i] = (float*) malloc(w * sizeof(float));

    // sample matrix filling
    for (int j = 0; j < w; j++)
        matrix[i][j] = (i + 1) * (j + 1);
    }

    return matrix;
}

它似乎工作正常，因为它不会崩溃，并且当我显示矩阵时，我具有与初始化它完全相同的值。尽管当我尝试释放矩阵时，如果行数小于列数，我会收到以下错误消息:

a.out(14284,0x7fff73cc9300) malloc: * error for object 0x9000000000000000: pointer being freed was not allocated * set a breakpoint in malloc_error_break to debug. Abort trap: 6"

我的释放例程如下:

void free_matrix(float **matrix, int h) {
    for (int i = 0; i < h; i++)
        free(matrix[i]);
    free(matrix);
}

Answer 1

试试这个

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

float **create_matrix(int h, int w)
{
    float **matrix = (float **)malloc(h*sizeof(float *));
    int i,j;
    for(i=0;i<h;i++){
       matrix[i] = (float *)malloc(w*sizeof(float));
    }
    for(i=0;i<h;i++){
        for(j=0;j<w;j++){
            matrix[i][j] = (i+1)*(j+1);
        }
    }
    return matrix;
}

int main()
{
    int h = 2, w = 3;
    float **matrix = create_matrix(h,w);
    int i,j;
    for(i=0;i<h;i++){
        for(j=0;j<w;j++){
            printf("%.2f ",matrix[i][j]);
        }
        printf("\n");
    }
    return 0;
}

开始操作之前需要分配内存。