Use the auto keyword in C++ STL

Question

I have seen code which use vector,

vectors;
s.push_back(11);
s.push_back(22);
s.push_back(33);
s.push_back(55);
for (vector::iterator i         


        

Answer 1

The auto keyword is simply asking the compiler to deduce the type of the variable from the initialization.

Even a pre-C++0x compiler knows what the type of an (initialization) expression is, and more often than not, you can see that type in error messages.

#include 
#include 
using namespace std;

int main()
{
    vectors;
    s.push_back(11);
    s.push_back(22);
    s.push_back(33);
    s.push_back(55);
    for (int it=s.begin();it!=s.end();it++){
        cout<<*it< > >, __gnu_debug_def::vector > >' to 'int' in initialization

The auto keyword simply allows you to take advantage of this knowledge - if you (compiler) know the right type, just choose for me!