sorting a vector

[michael1991j]

hello i am trying to sort a vector from least to greatest



vector<float> molarnum;

.... data being added to the vector....


sort(molarnum.begin(),molarnum.end());
float smallest = molarnum[0];




i am using #include <algorithm> to call upon to sort()
i keep geting a runtime error when i try sorting my vector.
does anybody know on how i can fix this or have a good function for sorting a vector ?

if anybody needs the full source i can give it , i just didnt want to post it due to so many lines of code

thank you michael

[laserlight]

Instead of providing the "full source", provide the smallest and simplest compilable program that demonstrates the error.

[Lindley]

"a runtime error" isn't very descriptive. What you've posted is fine, so odds are some other part of your program is corrupting memory.

[michael1991j]

let me rephrase my question then
i tried to aproach this program using arrays instead vector
the problem is when i call the array i get this in my debuger

that error C2057: expected constant expression


#include <iostream>

using namespace std;
int main()
{

int numele=2;
cin >> numele;
int elenum = numele;
float molarnum[elenum];


}

i tried using vectors to state this array is there a way i can fix this
sorry that i was not clear

[laserlight]

That is because arrays in C++ have a fixed size. You are trying to use variable length arrays, which do not exist in standard C++. Since you already tried with vectors, why not use them?

[michael1991j]

lets just say vectors are a little new to me

i am going to post my code


where the initiation of the vector is on line 231

i cant make a simple program because i dont know where i am going wrong

[laserlight]

I thought you were using std::sort(). If you only want to find the minimum element, use std::min_element().

[michael1991j]

can you help me on how to state that

[laserlight]

An example using a vector (though the vector is unnecessary in this case since I have a fixed size array)

#include <vector>
#include <algorithm>
#include <iostream>

int main()
{
    using namespace std;

    // Input array for convenience of initialisation.
    float input[] = {3.14, 2.718, 1.414, 4.5};

    vector<float> molarnum(input, input + sizeof(input) / sizeof(input[0]));

    vector<float>::iterator min_iter = min_element(molarnum.begin(), molarnum.end());
    if (min_iter != molarnum.end())
    {
        cout << "Minimum: " << *min_iter << endl;
    }
    else
    {
        cout << "The vector is empty." << endl;
    }
}

[_uj]

An example using a vector (though the vector is unnecessary in this case since I have a fixed size array)

There's a new STL container called array coming up in the new C++ standard.

http://www.codeguru.com/cpp/cpp/cpp_...le.php/c15257/

[laserlight]

There's a new STL container called array coming up in the new C++ standard.

I was aware of that, but the point of the example was to use the vector, not the array, so my note is concerning the fact that the array is purely to make initialisation of the vector easier in the absence of the initialisation syntax to be introduced by C++0x, despite the fact that the array alone would otherwise suffice for an example.

[_uj]

I was aware of that, but the point of the example was to use the vector, not the array, so my note is concerning the fact that the array is purely to make initialisation of the vector easier in the absence of the initialisation syntax to be introduced by C++0x, despite the fact that the array alone would otherwise suffice for an example.

I just wanted to add some information.

This new STL container called "array" will retire STL vector as the preferred replacement for C style arrays.

[kempofighter]

I just wanted to add some information.

This new STL container called "array" will retire STL vector as the preferred replacement for C style arrays.

That's fabulous. No offense, but how does that help us at the present time using compilers that do not implement the new standard?

[laserlight]

This new STL container called "array" will retire STL vector as the preferred replacement for C style arrays.

Generally, yes. However, in view that michael1991j attempted to use variable length arrays in C++, I daresay that std::vector is more appropriate here.

That's fabulous. No offense, but how does that help us at the present time using compilers that do not implement the new standard?

The array container is available in TR1, of which there are existing implementations. That said, we are detracting from the topic of this thread.