C++ NOW: comparison between signed and unsigned integer expressions (Freebsd, GCC, Gmake )

Question

I need some help from an error generated by the compiler.

I hope you can help me.

This is the error message:

FILE.cpp: In function 'int Gamble(std::vector<float, std::allocator<float> >&)':
FILE.cpp::6 :warning: comparison between signed and unsigned integer expressions
FILE.cpp:10: warning: comparison between signed and unsigned integer expressions

And here is the code :

typedef std::vector <std::string> TTokenVector;

int Gamble(std::vector<float>& vec_probs)
{
    float range = 0.f;
    for (int i = 0; i < vec_probs.size(); i++)    //Line  6
}
    float fProb = fnumber(0.f, range);
    float sum = 0.f;
    for (int idx = 0; idx < vec_probs.size(); idx++)   //LINE  10
{
        sum += vec_probs[idx];
        if (sum >= fProb)
            return idx;
}
    return -1;
}

The default compilator is freebsd ( GCC )

There are *loads* of duplicates here; please use the search facility before posting. — Oliver Charlesworth, Sep 27 '14 at 14:20

score 3 · Accepted Answer · answered Sep 27 '14 at 14:19

This is the culprit

for (int i = 0; i < vec_probs.size(); i++)

Try

for (size_t i = 0; i < vec_probs.size(); i++)

The int type is signed, the size_t type (returned from .size()) is unsigned.

The same warning will occur in your next for loop

(int idx = 0; idx < vec_probs.size(); idx++)

C++ NOW: comparison between signed and unsigned integer expressions (Freebsd, GCC, Gmake )

1 Answers1