C++ Lecture 4

Intro to Standard String Class

// Defines class string { ... };
#include <std/string.h>

• manages and manipulates strings of characters
  (good replacement for the likes of
    char buf[1024];)
• grows as needed
• has rich set of methods & overloaded operators
  (i.e., strcpy(), strcmp(), etc. no longer needed)
• can still get at C-style char * string if necessary.

#include <std/string.h>
int
main()
{
    string s, t;

    t = "hi";
    t.append(" there");
    cin >> s;
    cout << t << ' ' << s << endl;

    return 0;
}

More on Standard String Class

• string::size_type - type used to index characters in a string
• string::npos - contsant size_type that represents
  • no possition (e.g., failure to find something)
  • or `go to the end' (e.g., subtr() method)
• Commonly used string methods:
  const char *c_str(): return C-style string
  size_type length()
  bool empty()
  size_type find(char c, size_type n = 0);
  size_type find(const string&, size_type n = 0);
  string substr(size_type pos = 0,
     size_type n = npos)
• Commonly used overloaded operators:
  • == - contents of strings the same?
    (also !=, <, <=, >=, >)
  • = - assign a char *, char, or string
  • += - append a char *, char, or string
  • + - creates and returns a new string
• related functions:
  • ostream& << string&
    write a string
  • istream& >> string&
    read a (space delimited) string
  • getline(istream&, string&, char delim='\n')
    read a line (not including the \n)