int main()
{
char next4[4] ; 
 
while(!fileopen.eof())
{
        fileopen.read (next4, 4 ) ;
}
 
}

long next4;
 fileopen.read (&next4, sizeof(long) ) ;

int main()
{
char next4[4] ; 
int num;
while(!fileopen.eof())
{
        fileopen.read (next4, 4 ) ;
        num = *(int *)next4;
}
 
}

int num;
...
memcpy(&num, next4, sizeof(long));

char_traits<char>::char_type ch = next4[4] ;
char_traits<char>::int_type int_val ;
int_val = char_traits<char>::to_int_type (ch) ;

#include <iostream>
#include <string>
using namespace std ;
 
int main()
{
    char next4[4] = {0};
    int n = 123;
    memcpy(next4, &n, sizeof(int));
    char_traits<char>::char_type ch = next4[4] ;
    char_traits<char>::int_type int_val ;
    int_val = char_traits<char>::to_int_type (ch) ;
 
    cout << "int_val = " << int_val << "\n";
    return 0;
 
}