CODEWITHSUNDEEP
c++pointersdynamic-arrays
Tyler.z.yang
Tyler.z.yang

Reputation: 2450

C++ get length from two dimensional dynamic array

I have got stuck by the C++ two dimensional dynamic array. I want to get the array length. Here is the code:

#include <iostream>
using namespace std;
int dosomestuff(char **dict);
int main(){
    int x, y;
    char **dict;  
    cin>>x>>y;    // here to input the 'x'
    dict = new char *[x];
    for(i = 0; i < x; i++){
        dict[i] = new char[y];
        for(j = 0; j < y; j++){
            cin>>dict[i][j];
        }
    }
    dosomestuff(dict);
}
int dosomestuff(char **dict){
    int x, y;
    x = sizeof(*dict);     //8 not equal to the 'x'
                           //run in mac_64  I think this is the pointer's length
    y = strlen(dict[0]);   //this equal to the 'y' in function main
    cout<<x<<" "<<y<<endl;
    return 0;
}

What I want is in function dosomestuff to get the x equal the 'x' in function main.

How can I to get it? Can anybody help me ~? Thx a lot.

Upvotes: 1

Views: 90

Answers (1)

R Sahu
R Sahu

Reputation: 206607

sizeof(*dict) only gives you the sizeof(char*), which is not what you are hoping for.

There is no way of knowing the value of x from dict in dosomestuff. If you want to use char** for dict, your best option is to pass x and y to dosomestuff.

int dosomestuff(char **dict, int x, int y);

Since you are using C++, you can use:

std::vector<std::string> dict;

Then you would have all the information you need in dosomestuff if you pass that dict to it.

Upvotes: 4

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