Rezumat problemă

Expresie3

#335

Să se scrie un program care citește numărul natural n și determină suma S=1*2-2*3+3*4-...±n*(n+1).

Consola Candale Silviu (silviu) ușoară

Clasa 9 Algoritmi elementari Sume, produse, numărări

Rezolvă

Detalii

Problema	Expresie3	Operații I/O	tastatură/ecran
Limita timp	0.1 secunde	Limita memorie	Total: 64 MB / Stivă 8 MB
Id soluție	#64619356	Utilizator	Milea Maria (maria_milea)
Fișier	expresie3.cpp	Dimensiune	175 B
Data încărcării	18 Mai 2026, 22:22	Scor/rezultat	Eroare de compilare

Evaluare

Mesaj compilare

expresie3.cpp:1:2: error: invalid preprocessing directive #includeriostream
    1 | #includeriostream>
      |  ^~~~~~~~~~~~~~~~
expresie3.cpp: In function ‘int main()’:
expresie3.cpp:5:9: error: ‘cin’ was not declared in this scope
    5 |     for(cin>>x;x!-0; cin>>x)
      |         ^~~
expresie3.cpp:1:1: note: ‘std::cin’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
  +++ |+#include <iostream>
    1 | #includeriostream>
expresie3.cpp:5:17: error: expected ‘;’ before ‘!’ token
    5 |     for(cin>>x;x!-0; cin>>x)
      |                 ^
      |                 ;
expresie3.cpp:5:19: warning: for increment expression has no effect [-Wunused-value]
    5 |     for(cin>>x;x!-0; cin>>x)
      |                   ^
expresie3.cpp:5:20: error: expected ‘)’ before ‘;’ token
    5 |     for(cin>>x;x!-0; cin>>x)
      |        ~           ^
      |                    )
expresie3.cpp:5:5: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation]
    5 |     for(cin>>x;x!-0; cin>>x)
      |     ^~~
expresie3.cpp:5:22: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
    5 |     for(cin>>x;x!-0; cin>>x)
      |                      ^~~
expresie3.cpp:5:22: error: ‘cin’ was not declared in this scope
expresie3.cpp:5:22: note: ‘std::cin’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
expresie3.cpp:7:5: error: ‘cout’ was not declared in this scope
    7 |     cout<<S;
      |     ^~~~
expresie3.cpp:7:5: note: ‘std::cout’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?

Cum funcționează evaluarea?