CODEWITHSUNDEEP
c++stringvectoratoi
Ruzzle
Ruzzle

Reputation: 31

converting string vectors to int

I have to make a program that reads information for a student from a file, and I made a couple of vectors to keep all that information. But then I need to sum up the absences of all the students, so I need to convert them to integer, however when I try to the program runs, but crashes immediately when it reaches the atoi part.

while(!read.eof()) {
    if(i==4){
        i=0;
    }

    read>>b;

    if(i==0){ names.push_back(b); }
    if(i==1){ last_name.push_back(b); }
    if(i==2){ absences.push_back(b); }
    if(i==3){ unatoned.push_back(b); }
    i++;
}

int a = atoi(absences[0].c_str());

Upvotes: 3

Views: 113

Answers (2)

Guillaume Racicot
Guillaume Racicot

Reputation: 41820

You should change you absences vector to be a vector of int:

std::vector<int> abscences;

// rest of the code...

The read >> var instruction will take care of the conversion.

Of course, the >> operator will not write into the integer if it's invalid.

Upvotes: 0

Bathsheba
Bathsheba

Reputation: 234845

If absences remains empty then the behaviour of absences[0] is undefined.

Using absences.at(0) when absences is empty forces the compiler to throw an exception so is easier to work with.

Either way, for the number of absences, use simply

auto a = absences.size();

Upvotes: 3

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