what does this mean ?

Question

int *temp = new int[atoi(argv[3])];

what does the above statement mean ?Please explain in detail .

Answer 1

It allocates a int array with elements of the 3 program argument.

for example: main.exe foo bar 100 will allocated a array with 100 integers.

Answer 2

you declare a pointer to a newly allocated array of integers with the size determined by the numeric value that the string argv[3] (i.e. the 3rd command line argument) has

Answer 3

parses the string argv[3] into an int, then creates an array of ints of that size. Then it assigns the pointer to (the first element of) that array to temp.

Answer 4

In Detail:

int* temp //declares a pointer to int
int* temp = //that points to
int* temp = new //newly allocated memory
int* temp = new int [ //of type array of int of size 
int* temp = new int [ atoi ( //equal to the integer representation (atoi -> alphabetical to integer)
int* temp = new int [ atoi ( argv[3] //of the third command line argument passed to your program.

That is if your third command line arg is "5", temp will point to a dynamically allocated array of 5 ints

Answer 5

Pointers? New? Not very C++ish...

#include <vector>
#include <boost/lexical_cast.hpp>

int main(int argc, char** argv)
{
    std::vector<int> temp(boost::lexical_cast<int>(argv[3]));
}