Segmentation Fault (core dumped)

I'm working on a decoding program, and I'm having trouble with a string which I want to give a variable size, which causes me "Segmentation Fault (core dumped)" if I give it a constant size and then "str.resize" it, debugger tells me:
error: request for member ‘resize’ in ‘line’, which is of non-class type. The problem is with line 74.

Code:

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

string code = "the quick brown fox jumps over the lazy dog";
int x = code.length();

int checkCode(string a[], int size) {
    int numcode = 8;
    int numspace = 0;
    int numret = 0;
    for (int i = 0; i < size; i++) {
        string b = a[i];
        int c = b.length();
        if (c == x) {
            for (int j = 0; j < c; j++) {
                if (b[j] == ' ') numspace++;
            }
            if (numspace == numcode) {
                numret = i;
                i = size;
            }
        }
    }
    return numret;
}

string getCode(string d) {
    string dec = "abcdefghijklmnopqrstuvwxyz";
    char loc = ' ';
    int q = d.length();
    for (int i = 0; i < q; i++) {
        if (d[i] != ' ') {
            loc = d[i] - 'a';
            dec[loc] = code[i];
        }
    }
    return dec;
}

void decode(string s[], int size, string d, string name) {
    char loc = ' ';
    ofstream arch;
    arch.open(name.c_str());
    for (int i = 0; i < size; i++) {
        string n = s[i];
        int t = n.length();
        for (int j = 0; j < t; j++) {
            if (n[j] != ' ') {
                loc = n[j] - 'a';
                n[j] = d[loc];
            }
        }
        arch << n << endl;
    }
}

int main() {
    int num = 0,codeN,cont;
    string dec, name;

    cout << "Coded file name: ";
    cin >> name;

    //Open file and creates an array based on size
    ifstream arch;
    arch.open((name).c_str());
    while (getline(arch,dec)) {
        num++;
    }
    string line[30];
    line.resize(num);

    arch.clear();
    arch.seekg(0);
    cont = 0;
    while (!arch.eof()) {
        getline(arch,line[cont]);
        cont++;
    }
    arch.close();

    cout << "Decoded file name: ";
    cin >> name;

    codeN = checkCode(line,num);
    dec = getCode(line[codeN]);
    decode(line,num,dec,name);

    cout << "File ready: " << name << endl;

    return 0;
}

The problem is with line 74.

O_o

No. The problem is with you.

An array of thing is not an instance of thing; it is an array of thing.

Consider using a `std::vector<std::string>'; I don't see you doing this right without it.

Soma

And while you're at it, use push_back instead of resize. Read into a temp string, then push back.

Thank you for all the commentary. As a beginner it's helpful to get feedback on conventions to make my code better. I'm bumping myself in the head for trying to use an array in that way.

Is there such a function in C/C++ for resizing of arrays called 'resize'? Google doesn't help me find it, I want to guess it doesn't exist.

There is no such function, hence phantomotap's suggestion of using a std::vector instead.