Compilare: user.c: In function ‘main’: user.c:11:5: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] if((1+ sqrt(1+ 8 * nr)) /2 != floor((1+ sqrt(1+ 8 * nr)) /2)) ^ user.c:11:12: warning: incompatible implicit declaration of built-in function ‘sqrt’ [enabled by default] if((1+ sqrt(1+ 8 * nr)) /2 != floor((1+ sqrt(1+ 8 * nr)) /2)) ^ user.c:11:5: warning: implicit declaration of function ‘floor’ [-Wimplicit-function-declaration] if((1+ sqrt(1+ 8 * nr)) /2 != floor((1+ sqrt(1+ 8 * nr)) /2)) ^ user.c:11:35: warning: incompatible implicit declaration of built-in function ‘floor’ [enabled by default] if((1+ sqrt(1+ 8 * nr)) /2 != floor((1+ sqrt(1+ 8 * nr)) /2)) ^ user.c:14:9: warning: ‘return’ with no value, in function returning non-void [enabled by default] return; ^ user.c:16:18: warning: incompatible implicit declaration of built-in function ‘sqrt’ [enabled by default] int n = ((1+ sqrt(1+ 8 * nr)) /2); ^ user.c:8:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sume.in","r",stdin); ^ user.c:9:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sume.out","w",stdout); ^ user.c:10:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&nr); ^ user.c:19:15: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&v[i]); ^