stof hangs on runtime

Question

I am reading in times from a list in a text file, with format in the following manner

1      00:03.56
2      00:06.12

I need to take in every other line, and do some analysis on this, but, when I read it in and try to use the "std::stof()" function to convert this to a usable form, it hangs on the very first conversion (10+ minutes at a single core on a 4 core i7). The relevant code is attached.

while (tf.is_open()) {
i++;
//std::cout << i << std::endl;
std::getline(tf, full);
std::stringstream tbreak;
tbreak.str(full);
int k = 0;
std::string milsec;
while (std::getline(tbreak, time, ' '))
{
//  std::cout << k << std::endl;
    if (k % 2 == 0) {
        k++;
        continue;
    }
    std::stringstream hrminsec;
    hrminsec.str(time);

    int m = 0;
    while (std::getline(hrminsec, brokentime, ':'))
    {
        //std::cout << brokentime << std::endl;

        if (m % 2 == 0)
        {
            m++;
            continue;
        }
        //if (m % 2 == 1) time = brokentime;
        //if (m % 3 == 2) milsec =brokentime;
        if (brokentime == "time" || brokentime == "times")
        {
            m++;
            continue;
        }
        //std::cout << brokentime << std::endl;
        std::stringstream further;
        int n = 0;
        further.str(brokentime);
        std::string temp;
        while (std::getline(further, temp, '.'))
        {
            //std::cout << temp << std::endl;
            if (n % 2 == 0) time = temp;
            time.erase(0, time.find_first_not_of('0'));
            //std::cout<<time <<std::endl;
            if (n % 2 == 1)milsec = temp;
            n++;
            if (i % 2 == 0) {
                float temp1 = std::stof(time);
                std::cout << temp1 << std::endl;
                float temp2 = std::stof(milsec);
                temp1 = temp1 + 0.01*temp2;
                int j = i - 2;
                t[j] = temp1;
                std::cout << j << std::endl;
            }
        }


        m++;
    }
    k++;
}

This compiles fine, and most of the sub loops were to get the compilation correct. I am using Visual Studio 15 on Windows 10 if that matters.

Please post full code so that it is easier to compile and debug code so that others can test it easily. — Shiv, Dec 17 '17 at 08:13
there is a lot of while loops here doing getline. you said you were reading from one file ? i would expect one while loop reading each line then deciding what to do with the line. — AndersK, Dec 17 '17 at 08:21
I have added it to a github directory here (https://github.com/silas-gross/Milikan_data_analysis) — Silas K Grossberndt, Dec 17 '17 at 22:56
Sample data file has been added and updates have been made, the issue arose from placing the "if" loop with the stof one layer to deep, it was hanging on a null defined string. Now just having issues with an stof argument — Silas K Grossberndt, Dec 18 '17 at 00:58

score 0 · Answer 1 · answered Feb 22 '23 at 18:05

That "hang" is almost surely* an (unhandled) exception thrown by stof. And that exception is very likely the result of an empty string read from the input, or one that really doesn't look like a float.

The exact, specific cause that derails the input readings is hard to tell, but that's where you should be looking. I can see you've debugged time, but also check if milsec had been correctly read, too.

* I've had this exact same problem myself. But don't ask, why the occasional silent hang is the way of "handling" unhandled exceptions in MSVC (also in debug builds).

stof hangs on runtime

1 Answers1