How to Print an Array over another Array in C? - c

Question

Im writing a program where it will compare the elements in 2 separate 2d array and check for elements that overlap each other. It then prints out an array where elements in both the 2d array are present but the elements in the second 2d array will replace the elements of the first array when the elements overlap each other. How do I overlap these two array into 1 array?
void tile1(char pat1[13][13]) //to arrange the pattern
{
int r,c;
for(r=0;r<13;r++)
{
for(c=0;c<13;c++)
{
if(r==0 || r==12) // top and bottom border
{
pat1[r][c] = '-';
}
else if(r>0 && r<6 && c>=0 && c<6)
{
pat1[r][c] = '^';
}
else
{
pat1[r][c] = ' ';
}
}
}
}
void tile3(char pat3[13][13]) //to arrange the pattern
{
int r,c;
for(r=0;r<13;r++)
{
for(c=0;c<13;c++)
{
if(r==0 || r==12)
{
pat3[r][c] = '-';
}
else if(r==c || r+1==c || r-1==c)
{
pat3[r][c] = 'X';
}
else
{
pat3[r][c] = ' ';
}
}
}
}
This is my codes for the 'overlap':
void overlap(char pat1[13][13], char pat2[13][13])
{
int r,c;
for(r=0;r<13;r++)
{
printf("|");
for(c=0;c<13;c++)
{
if(pat1[r][c]!=' ' || pat2[r][c]!=' ')
{
pat1[r][c] == pat2[r][c];
}
else
{
pat1[r][c] == pat1[r][c];
}
printf(" %c ", pat1[r][c]);
}
printf("|\n");
}
}
When I run the program, it prints an empty 2d array? Which part of the code should i modify, im pretty sure its the overlap function right?

Answer 1

The following test is incorrect:
if (pat1[r][c]!=' ' || pat2[r][c]!=' ') {
pat1[r][c] == pat2[r][c];
}
Consider the case where pat1 has a non-space and pat2 has a space. You want to leave pat1 alone, but instead this test will succeed, and it will be replaced with the space from pat2.
You can change it to:
if (pat1[r][c] == ' ') {
pat1[r][c] == pat2[r][c];
}
That will replace the pat1 entry with whatever is in pat2 (space or otherwise), if the pat1 entry is a space.
You can delete the else clause as well, since it has no effect.