Compilare: user.cpp: In function ‘bool is_ok()’: user.cpp:17:18: warning: left operand of comma operator has no effect [-Wunused-value] for(i=0,k=0;i<n,k<n;i++,k++) ^ user.cpp:18:22: warning: left operand of comma operator has no effect [-Wunused-value] for(j=0,l=0;j<n,l<n;j++,l++) ^ user.cpp:27:17: warning: left operand of comma operator has no effect [-Wunused-value] for(i=0,k=0;i<n,k<n;i++,k++) ^ user.cpp:28:24: warning: left operand of comma operator has no effect [-Wunused-value] for(j=n-1,l=0;j>=0,l<n;j--,l++) ^ user.cpp:37:21: warning: left operand of comma operator has no effect [-Wunused-value] for(i=n-1,k=0;i>=0,k<n;i--,k++) ^ user.cpp:38:22: warning: left operand of comma operator has no effect [-Wunused-value] for(j=0,l=0;j<n,l<n;j++,l++) ^ user.cpp:47:20: warning: left operand of comma operator has no effect [-Wunused-value] for(i=n-1,k=0;i>=0,k<n;i--,k++) ^ user.cpp:48:24: warning: left operand of comma operator has no effect [-Wunused-value] for(j=n-1,l=0;j>=0,l<n;j--,l++) ^ user.cpp:60:18: warning: left operand of comma operator has no effect [-Wunused-value] for(i=0,k=0;i<n,k<n;i++,k++) ^ user.cpp:61:22: warning: left operand of comma operator has no effect [-Wunused-value] for(j=0,l=0;j<n,l<n;j++,l++) ^ user.cpp:70:17: warning: left operand of comma operator has no effect [-Wunused-value] for(i=0,k=0;i<n,k<n;i++,k++) ^ user.cpp:71:24: warning: left operand of comma operator has no effect [-Wunused-value] for(j=n-1,l=0;j>=0,l<n;j--,l++) ^ user.cpp:80:21: warning: left operand of comma operator has no effect [-Wunused-value] for(i=n-1,k=0;i>=0,k<n;i--,k++) ^ user.cpp:81:22: warning: left operand of comma operator has no effect [-Wunused-value] for(j=0,l=0;j<n,l<n;j++,l++) ^ user.cpp:90:20: warning: left operand of comma operator has no effect [-Wunused-value] for(i=n-1,k=0;i>=0,k<n;i--,k++) ^ user.cpp:91:24: warning: left operand of comma operator has no effect [-Wunused-value] for(j=n-1,l=0;j>=0,l<n;j--,l++) ^