c++ - Symbol vector could not be resolved -

#include <iostream> #include <vector>  using namespace std;   class block{ public:     long nx,ny;     vector<long> s;     block(long &x, long &y):nx(x),ny(y),vector<long> s((x+1)*(y+1),0) {} };  int main() {     block b(2,2);     for(int i=1;i<=9;i++) {         cout<<b.s(i);     }      cout << "!!!hello world!!!" << endl; // prints !!!hello world!!!     return 0; } 

compiled , error message shows symbol "vector" not resolved. mistake? want define class contain variable dimension vector initialize.

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#include <iostream> #include <vector>  using namespace std;   class block{ public:     long nx,ny;     vector<long> s;     block(long &x, long &y):nx(x),ny(y),s((x+1)*(y+1),0) {} };  int main() {     block b(2,2);     for(int i=0;i<=9;i++) {         cout<<b.s[i];     }      cout << "!!!hello world!!!" << endl; // prints !!!hello world!!!     return 0; } 

still got problem @ block b(2,2); error message:no instance of constructor "block::block" matches argument list

why? thanks!

firstly:

  vector<long> s((x+1)*(y+1),0) 

should be:

  s((x+1)*(y+1),0) 

should not repeat type s. meanwhile constructor should be:

  block(const long &x, const long &y):     nx(x), ny(y), s((x + 1) * (y + 1), 0)   {   } 

if need reference. since otherwise, when

 block b(2,2); 

inside main, give error because constructor takes long&, passing int constants. deep reason related lvalue , rvalues: integer constants rvalues, however, long& reference non-const long, lvalue reference. according blog: lvalues, rvalues , references

an lvalue reference (to non-const type) reference can initialized lvalue. well, lvalues not render const or volatile types. rvalue reference (to non-const type) reference can initialized rvalue (again, rvalues not designate const or volatile types). lvalue reference const type reference can initialized rvalues , lvalues alike (rendering constant , non-constant types).

further, according c++11 standard: section 4.1 standard conversions:

standard conversions implicit conversions defined built-in types. standard conversion sequence sequence of standard conversions in following order:

— 0 or 1 conversion following set: lvalue-to-rvalue conversion, array-to-pointer conversion, , function-to-pointer conversion.

— 0 or 1 conversion following set: integral promotions, floating point promotion, integral conversions, floating point conversions, floating-integral conversions, pointer conversions, pointer member conversions, , boolean conversions.

— 0 or 1 qualification conversion.

there no rvalue-to-lvalue conversion. why saw compile error. adding const before long&make able initialized rvalues, that's why error goes away after change.

secondly,

  cout<<b.s(i); 

should be:

cout<<b.s[i]; 

you should use [] access vector elements.

thirdly, vector index starts 0,

for(int i=1;i<=9;i++) 

should be

for(int i=0;i<9;i++) 

otherwise, index out of bounds. see working example here: http://ideone.com/ylt3mg