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How to create vectors?

I need a little help understanding vectors in C++?

  • I have a header.h, a main.cpp, and a function.cpp files. My header contains a class called Name, this is simply a test for a much bigger program I'm doing. what i cannot figure out is how to call a vector in a function. class Name{ public: Name(); Name(string, double); ~Name(); void setName(string aname); void setAmount(double anamount); string getName(); double getAmount(); void printName(); void Name::Amountot(); void vecfill(); private: string name; double amount; }; That is my Name class. Say i wanted to make a vector. vector<Name> NameLot; I would then create a Class, Name name1; That last part being in the main program, how would i be able to get my vector into a function for example for printing or even filling the vector? I can do it within the main program but my teacher wants everything in separate functions and having the main program only calling them. I know for a array it would look something like, void Name::vecfill(int Namelot[ ]); however with vectors void Name::vecfill(vector<Name> Namelot) doesn't work, nor does it let me add vector<Name> Namelot to the class as a private. I really need help and appreciate advice you guys can give.

  • Answer:

    Just see the following code which explains how to maintain strings in a vector and print all of them one after another. #include <iostream> #include <vector> #include <string> using namespace std; main() { vector<string> SS; SS.push_back("The number is 10"); SS.push_back("The number is 20"); SS.push_back("The number is 30"); cout << "Loop by index:" << endl; int ii; for(ii=0; ii < SS.size(); ii++) { cout << SS[ii] << endl; } cout << endl << "Constant Iterator:" << endl; vector<string>::const_iterator cii; for(cii=SS.begin(); cii!=SS.end(); cii++) { cout << *cii << endl; } cout << endl << "Reverse Iterator:" << endl; vector<string>::reverse_iterator rii; for(rii=SS.rbegin(); rii!=SS.rend(); ++rii) { cout << *rii << endl; } cout << endl << "Sample Output:" << endl; cout << SS.size() << endl; cout << SS[2] << endl; swap(SS[0], SS[2]); cout << SS[2] << endl; } If you want to print all the elements of a vector having strings as above print(vector<string> SS) { vector<string>::const_iterator cii; for(cii=SS.begin(); cii!=SS.end(); cii++) { cout << *cii << endl; } } Now, you want to insert your Name objects vector <Name> NameLot; NameLot.push_back( *(new Name()); //I am applying * as constructor returns pointer and vector is declared to hold Name type objects not pointers. NameLot.push_back(*( new Name("Rana", 1.22)); You can write method as explained above.

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Just see the following code which explains how to maintain strings in a vector and print all of them one after another. #include <iostream> #include <vector> #include <string> using namespace std; main() { vector<string> SS; SS.push_back("The number is 10"); SS.push_back("The number is 20"); SS.push_back("The number is 30"); cout << "Loop by index:" << endl; int ii; for(ii=0; ii < SS.size(); ii++) { cout << SS[ii] << endl; } cout << endl << "Constant Iterator:" << endl; vector<string>::const_iterator cii; for(cii=SS.begin(); cii!=SS.end(); cii++) { cout << *cii << endl; } cout << endl << "Reverse Iterator:" << endl; vector<string>::reverse_iterator rii; for(rii=SS.rbegin(); rii!=SS.rend(); ++rii) { cout << *rii << endl; } cout << endl << "Sample Output:" << endl; cout << SS.size() << endl; cout << SS[2] << endl; swap(SS[0], SS[2]); cout << SS[2] << endl; } If you want to print all the elements of a vector having strings as above print(vector<string> SS) { vector<string>::const_iterator cii; for(cii=SS.begin(); cii!=SS.end(); cii++) { cout << *cii << endl; } } Now, you want to insert your Name objects vector <Name> NameLot; NameLot.push_back( *(new Name()); //I am applying * as constructor returns pointer and vector is declared to hold Name type objects not pointers. NameLot.push_back(*( new Name("Rana", 1.22)); You can write method as explained above.

James Bond

Probably you're not defining the type of the vector you want to pass in the function. You can do something like this: 1 2 3 4 void pass_vector(vector<int> v_int) { // code } In previous example i passed a specific type to vector, which is int, but if you want pass a type in parameter you need to create a template function: 1 2 3 4 5 template <typename T> void pass_vector(vector<T> v) { //code here } Help: http://www.cplusplus.com/doc/tutorial/templates.html

Black Stone

Probably you're not defining the type of the vector you want to pass in the function. You can do something like this: 1 2 3 4 void pass_vector(vector<int> v_int) { // code } In previous example i passed a specific type to vector, which is int, but if you want pass a type in parameter you need to create a template function: 1 2 3 4 5 template <typename T> void pass_vector(vector<T> v) { //code here } Help: http://www.cplusplus.com/doc/tutorial/templates.html

Black Stone

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