Segmentation Fault in C associated with a game called Fill-Zone

Question

I'm creating a game which is common known as fill-zone but with numbers. However I'm having issues with segmentation fault. Can you tell me why? Here is my code:

#include 
#include 

void help(int a[20][60],int b[20][60],int i, int j)
{
    if(i-1<20 && i-1>=0 && (i-1!=0 || j!=0) && a[i-1][j]==a[0][0])
    {
        b[i-1][j]=1;
        help(a,b,i-1,j);
    }
    if(j-1<60 && j-1>=0 && (i!=0 || j-1!=0) && a[i][j]==a[0][0])
    {
        b[i][j-1]=1;
        help(a,b,i,j-1);
    }
    if(i+1<20 && i+1>=0 && a[i+1][j]==a[0][0])
    {
        b[i+1][j]=1;
        help(a,b,i+1,j);
    }
    if(j+1<60 && j+1>=0 && a[i][j+1]==a[0][0])
    {
        b[i][j+1]=1;
        help(a,b,i,j+1);
    }
}

void game(int a[20][60],int b[20][60],int i,int j)
{
    int c;

    scanf("%d",&c);

    for (i=0;i<20;i++)
        for (j=0;j<60;j++)
            if (b[i][j]==b[0][0])
                a[i][j]=c;
}

int end(int a[20][60])
{
    int i,j;

    for (i=0;i<20;i++)
        for (j=0;j<60;j++)
            if (a[i][j]!=a[0][0])
                return 1;

    return 0;
}

int main(int argc, char *argv[]) { 
    int a[20][60],b[20][60],i,j,k;

    srand (time(NULL));

    k=0; 
    for (i=0;i<20;i++) 
        for (j=0; j<60; j++) 
        { 
            b[i][j]=0;
            a[i][j]= rand() % 5 + 1 ; 
        } 

    b[0][0]=1;
    for (i=0;i<20;i++) 
        for (j=0; j<60; j++) 
        { 
            if (j==59)
                printf("%d\n",a[i][j]); 
            else
                printf("%d",a[i][j]); 
        }

    do
    {
        help(a,b,0,0);
        game(a,b,0,0); 
        for (i=0;i<20;i++) 
            for (j=0; j<60; j++) 
            { 
                if (j==59)
                    printf("%d\n",a[i][j]); 
                else
                    printf("%d",a[i][j]); 
            }

        for (i=0;i<20;i++) 
            for (j=0; j<60; j++) 
            { 
                if (j==59)
                    printf("%d\n",b[i][j]); 
                else
                    printf("%d",b[i][j]); 
            }
    }
    while (end(a)==1); 

    return 0; 
}

When I debug it and run it, it works fine for a couple of times but then it says segmentation fault and shows me the line help(a,b,i-1,j);

What should I do? Do you have any suggestions?

Answer 1

You are not checking if both i and j are inside bounds simultaneously -:

In the first if() block, you are not checking if j<60 && j>=0.
Similarly in the second if() block, you are not checking if i<20 && i>=0.
Same for the rest of the 2 if() blocks.