how to convert int to vector<int>?

When I assign int to vector I get an error says "conversion from 'int' to non-scalar type 'std::vector<int, std::allocator<int> >' requested", what should I do? I have vector varr(4, -1); what is the right way to 开发者_开发百科do "varr[2] = 3"?

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They're two different types. If you want to add an int to a vector<int> do something like:

std::vector<int> vec;
vec.push_back(10);

Update: To set an element within the vector:

std::vector<int> vec(16, 0); // Create a 16 element vector containing all 0's
vec[4] = 10; // Sets the 5th element (0 based arrays) to 10

There appears to be a thorough codeguru tutorial which might be of interest.

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A vector is a collection of ints. You can not assign an int to the collection, you add it to the collection using the push_back() function:

std::vector<int> manyInts;
int oneInt = 42;
manyInts.push_back(oneInt);

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If you want to add the int to to a vector<int> you should use push_back:

vector<int> v;
int i = 5;
v.push_back(i);

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int sum = 468;
vector<int> v;
while(sum!=0){
 v.push_back(sum%10);
        sum /= 10;
    }
reverse(v.begin(), v.end());