在C中将数据从一个矩阵复制到另一个

Question

I have two matrix dynamically allocated.I want to copy all the data from the first matrix and center it by a border to the second one.Here is my code which apparently does not work properly so I would be grateful for some help:

The first matrix:

    unsigned char ** sudo=(unsigned char **) malloc (width*sizeof (unsigned char*));

if ( sudo != NULL){
    for (k=0; k<width ;k++){
        sudo[k] =(unsigned char*) calloc (height,sizeof (unsigned char));
    }
}

The second one:

unsigned char ** fmatr=(unsigned char **) malloc ((width+border)*sizeof (unsigned char*));

if ( fmatr != NULL){
    for (k=0; k<(width+border) ;k++){
        fmatr[k] =(unsigned char*) calloc ((height+border),sizeof (unsigned char));
    }
}

How I center first matrix in the middle of the second one:

    for(i=0,k=0;i<(width+border);i++,k++){
      for(j=0,l=0;j<(height+border);j++,l++){
        if((i>(2*border)) && (j>(2*border))){
            fmatr[i][j]=sudo[k][l];
        }
    }
}

Any ideas?

Answer 1

Since the first matrix has width x height entries, you want to loop from 0 to width-1 (not width-1+border) and from 0 to height-1 (not height-1+border). Similarly, you want to add border/2 to the index of the second array when assigning.

for(i=0;i<width;i++){
  for(j=0;j<height;j++){
    fmatr[i+(border/2)][j+(border/2)]=sudo[i][j];
  }
}