How do I determine the size of an array?

Question

So I'm trying to have the user enter strings that will be put into an array with the maximum size of 50 strings. Whenever the user enters "stop", I want the loop to stop and the array to cutoff there.

I then want to read the array back to the user. I tried running this and got a really weird error. Can someone explain to me why this doesn't work and how I would fix it? Thanks.

int main(int argc, const char * argv[]){

    string array[50];

    // Get's inputs for array
    for(int i = 0; i < 50; i++){
        cout << "Enter string: ";
        getline(cin, array[i]);

        if(array[i]== "stop"){
            array[i] = "\0";
            break;
        }

     }

    // Reads inputs from array
    for(int i = 0; i < sizeof(array); i++){
        cout << array[i] << "\n";
    }

    return 0;


}

I don't know why I'm getting down voted so hard?

Does it have to be an array? This type of thing is much better suited to vectors — Leon, May 06 '15 at 06:03
If your book covers arrays before vectors, it is highly suspect. Every modern C++ book does it the other way around. — fredoverflow, May 06 '15 at 06:16
@Suds2 Don't be a dummy, change your book. [Here](http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) is a list that you can choose from. — khajvah, May 06 '15 at 06:41

score 3 · Answer 1 · edited May 06 '15 at 07:06

Use std::vector for your task. It has the method push_back() where you can add elements dynamically. Also you can check the size of the vector easily by calling vector.size().

int main(int argc, const char * argv[]){

    vector<std::string> array;

    // Get's inputs for array
    for(int i = 0; i < 50; i++){
        cout << "Enter string: ";
        string line;
        std::getline(cin, line);
        array.push_back(line);

        if(array[i]== "stop"){
            array[i] = "\0";
            break;
        }

     }

    // Reads inputs from array
    for(int i = 0; i < array.size(); i++){
        cout << array[i] << "\n";
    }

    return 0;
}

In your code you would have to implement a counter that counts, how many inputs the user did.

score 0 · Answer 2 · answered May 06 '15 at 06:10

Normally you would use vectors, but since you have not reached that section of the book, I guess they want you to solve it with C-style arrays.

You can get the length of a C-style array like this

int size = (sizeof(array)/sizeof(*array)

But since you know the maximum number of entries are 50 and that you must stop when you reach the word stop, maybe you rather want this

for(int i = 0; i < 50; i++){
    if (array[i] == '\0')
        break;
    cout << array[i] << "\n";
}

score -2 · Answer 3 · answered May 06 '15 at 06:12

-2

I just implemented a loop to find out how long the array is.

// Determines how long the array is
    for(int i = 0; i < 50; i++){

        if(array[i] == "\0"){
            break;
        }

        counter++;
    }

answered May 06 '15 at 06:12

Suds2

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in the first loop, before breaking you can set the counter. counter = i ; right ? – Dinushan May 06 '15 at 06:16

How do I determine the size of an array?

3 Answers3