// string2num.cpp    YBM assisted by namehere05, et al.
// String to char conversion, char to numeric conversion using strtod() illegal entries will be ignored.
// Formatted output
// Must compile using CODE::BLOCK
// Borland 5.02 does not work
#include <stdio.h>
#include <conio.h>
#include <iostream>
#include <string>
#include <stdlib.h>
#include <fstream>
#include <iomanip>
using namespace std;
int c=0;
 
// Subroutine to fix decimal places
void decima(int &dec)
{
cout << setiosflags(ios::fixed |ios::showpoint) << setprecision(dec);
}
 
void waiting()
{
cout << "\n\nEsc to Exit.\n";
c=getch();
}
char *endptr;
double weight=0;
 
int main()
{
  system ("color 0a");     // green text on black background
  string concate;         // declare a string variable
  int len; //  find out the number of characters in the string
  cout << "\n\nThis program uses copy() and c_str() to convert string to char (c-string), \nthen char to numeric. Illegal entries will be ignored instead of program crashing";
  cout << "\n\nNormal rather than exponential and decimal places can be preset.\n\n";
  do
  {
    int dec=10;
    decima(dec);
    cout << "\n\nEnter Weight: ";
    getline(cin, concate);  // input string
    len=concate.length();  //find the number of characters in the string
    char xxc[len];  // initialize array
    concate.copy( xxc, len ); //fills array in order with characters from the string
    char const * c2 = concate.c_str();     // using c_str()
    weight=strtod(xxc,&endptr);
    cout << "\nWeight from copy()  : " << weight;
    weight=strtod(c2,&endptr);
    cout << "\nWeight from c_str() : " << weight;
    cout << "\n\nWeight displayed    : " << setw(20) << weight << endl;
    waiting();
  } while (c !=27);
return 0;
}

// string5    originally written by namehere05.
#include <iostream>
#include <string>
using namespace std;
int main() {
  system ("color 0a");     // green text on black bkgrd
  double numeric;
  string str;
  char *endptr;
  char * c = "No cover!";     // declaration of c-style string
  char chax[] = "123.45";  // Declaraition of c-style string
  string ch = "123.45";   // Decalration of c-style string
  string* pc;
  str = chax; //you can assign a c-string to a string
 
  cout << "\nSTRING MANPULATIONS AND CONVERSION TO NUMERIC VARIABLE\n\n";
  cout << "\nC-STYLE STRING chax";
  char *cstr = "Hello";
  printf( "\nThe second character of %s is %c.\n",
  cstr, cstr[1] );
  cout << "\nBefore replacement of 3rd char with X, chax : " << chax;
  chax[2]='X';
  cout << "\nAfter replacement of 3rd char with X,chax   : " << chax;
  chax[2]='3';
  cout << "\nAfter replacement of 3rd char with 3, chax  : " << chax;
  cout << "\n\nC++ STRING str and C-STYLE STRING chax MANIPULATION ";
  cout << "\n\nstr's initial value  : "<< str;
  str[3]='0';//you can access the string as if it were an array
  cout << "\nstr after str[3]='0' : " << str;
  pc = &ch; // pc is assigned address of c
  cout << "\n\nch is assigned value          : " << ch;
  cout << "\nAddress of &ch assigned to pc : " << pc;
  cout << "\nContent pointed by *pc        : " << *pc;
  cout << "\n\nchax c-style = " << chax ;
  str=chax;
  cout << "\nstr = chax   = " << str << endl ;
  //cout << "\nc2 from conv = " << c2 << std::endl ;
 
  //   C-style string manipulation
 
  chax[3] = 'h';
  cout << "\nafter chax[3] = 'h', content of chax is : " << chax;
  str[3]='0';
  cout << "\nafter str[3] = '0', content of str is   : " << str;
  char const * c2 = str.c_str(); //it has to be const
  numeric = strtod(chax,&endptr);
  cout << "\n\nnumeric from strtod conversion of chax ignoring illegal char onwards  : " << numeric;
  numeric = strtod(c2,&endptr);
  cout << "\n\nnumeric from strtod conversion of str where all numbers are converted : " << numeric;
 
  std::cout << "\n\n";
  system("pause");
}