In C++, a string of characters is represented by a series of bytes corresponding to each of its characters, all of which end with an additional byte of zero code. A string of characters occupies a n+1 bytes location in memory.

#include <iostream>
using namespace std ;
int main()
{ 
    char * adr ;
    adr = "Hello" ;
    while (*adr)
    { 
        cout << *adr ;
        adr++ ;
    }
    return 0;
}
// Output : Hello

char * adr ;

• reserves the location for a pointer on a character (or a sequence of characters).
• For the constant : "Hello"
  • the compiler has created in memory the corresponding suite of bytes but, in the assignment:
• adr = "Hello"
  • The Hello notation has as value its address, not the value of the string itself; we find here the same phenomenon as for the arrays.

Reading and writing C-Style Strings

#include <iostream>
using namespace std ;
int main()
{ 
    char name [20], firstName [20], city [25] ;
    cout << " what is your city : " ;
    cin >> city ;
    cout << " give your name and first name : " ;
    cin >> name >> first name ;
    cout << "hello dear" << first name << " "<< name << " who lives in " << city ;
    return 0;
}
//Output
// what is your city : Ottawa
// give your name and first name : Leblanc Yves
// hello dear Yves Leblanc who lives in Ottawa

Initialization of arrays by Strings

char ch[20] ; – ch here is a constant pointer that corresponds to the address that the compiler has attributed to the array ch; it's not lvalue. Therefore, it cannot be given any other value (such as: ch = "hello"). – In C the characters array is initialized using a constant string

char ch[20] = "hello" ; which is equivalent to a ch Initialization by a list of characters: char ch[20] = {'h','e′, 'l′, 'l′, 'o′, '\0′ } – the 14 characters not explicitly initialized will be:

- initialized to zero (static class array): in this case, the omission of character \0 would not be (here) serious

(unless 20 characters had been provided!);

- Random (automatic class array): In this case, the omission of character \0 would be much more

troublesome.

- C++ authorizes the omission of the size of an array when it is made, when accompanied by an initialization,one can write:

char message[] = "hello" ;

• which reserves an array, called message, of 6 characters (considering the end 0).

Arguments transmitted to main function

#include <iostream>
using namespace std ;
main (int nbarg, char * argv[])
{ 
    int i ;
    cout << " my program name is : " << argv[0]<< "\n" ;
    if (nbarg>1) for (i=1 ; i<nbarg ; i++)
    cout << " argument number " << i << " : " << argv[i] << "\n" ;
    else cout << " no arguments \n" ;
}
// ----------------------Code output-----------------------------------------
// my program name is : XXX.exe
// argument number 1 : data.dat
// argument number 2 : output.txt