Compilare: user.cpp: In function ‘void f(int, int)’: user.cpp:24:18: warning: suggest parentheses around comparison in operand of ‘==’ [-Wparentheses] o[x][y-1]==o[x+1][y-1]==o[x+1][y]==o[x][y]==0; ^ user.cpp:24:31: warning: suggest parentheses around comparison in operand of ‘==’ [-Wparentheses] o[x][y-1]==o[x+1][y-1]==o[x+1][y]==o[x][y]==0; ^ user.cpp:24:42: warning: suggest parentheses around comparison in operand of ‘==’ [-Wparentheses] o[x][y-1]==o[x+1][y-1]==o[x+1][y]==o[x][y]==0; ^ user.cpp:24:51: warning: statement has no effect [-Wunused-value] o[x][y-1]==o[x+1][y-1]==o[x+1][y]==o[x][y]==0; ^