Compilare: user.cpp: In function ‘int main()’: user.cpp:4:92: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int n,a[101][101];int main(){int i,j,k;freopen("royfloyd.in","r",stdin);freopen("royfloyd.out","w",stdout);scanf("%d",&n);for (i=1;i<=n;i++)for (j=1;j<=n;j++){scanf("%d",&a[i][j]);if (a[i][j]==0)a[i][j]=oo;}for (k=n;k>=1;k--) for (i=1;i<=n;i++) for (j=1;j<=n;j++) if (a[i][j]>a[i][k]+a[k][j]) a[i][j]=a[i][k]+a[k][j];for (i=1;i<=n;i++){for (j=1;j<=n;j++) {if (i==j) a[i][j]=0; printf("%d ",a[i][j]);} printf("\n");}return 0;} ^ user.cpp:4:127: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int n,a[101][101];int main(){int i,j,k;freopen("royfloyd.in","r",stdin);freopen("royfloyd.out","w",stdout);scanf("%d",&n);for (i=1;i<=n;i++)for (j=1;j<=n;j++){scanf("%d",&a[i][j]);if (a[i][j]==0)a[i][j]=oo;}for (k=n;k>=1;k--) for (i=1;i<=n;i++) for (j=1;j<=n;j++) if (a[i][j]>a[i][k]+a[k][j]) a[i][j]=a[i][k]+a[k][j];for (i=1;i<=n;i++){for (j=1;j<=n;j++) {if (i==j) a[i][j]=0; printf("%d ",a[i][j]);} printf("\n");}return 0;} ^ user.cpp:4:142: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int n,a[101][101];int main(){int i,j,k;freopen("royfloyd.in","r",stdin);freopen("royfloyd.out","w",stdout);scanf("%d",&n);for (i=1;i<=n;i++)for (j=1;j<=n;j++){scanf("%d",&a[i][j]);if (a[i][j]==0)a[i][j]=oo;}for (k=n;k>=1;k--) for (i=1;i<=n;i++) for (j=1;j<=n;j++) if (a[i][j]>a[i][k]+a[k][j]) a[i][j]=a[i][k]+a[k][j];for (i=1;i<=n;i++){for (j=1;j<=n;j++) {if (i==j) a[i][j]=0; printf("%d ",a[i][j]);} printf("\n");}return 0;} ^ user.cpp:4:200: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int n,a[101][101];int main(){int i,j,k;freopen("royfloyd.in","r",stdin);freopen("royfloyd.out","w",stdout);scanf("%d",&n);for (i=1;i<=n;i++)for (j=1;j<=n;j++){scanf("%d",&a[i][j]);if (a[i][j]==0)a[i][j]=oo;}for (k=n;k>=1;k--) for (i=1;i<=n;i++) for (j=1;j<=n;j++) if (a[i][j]>a[i][k]+a[k][j]) a[i][j]=a[i][k]+a[k][j];for (i=1;i<=n;i++){for (j=1;j<=n;j++) {if (i==j) a[i][j]=0; printf("%d ",a[i][j]);} printf("\n");}return 0;} ^