A Review of the String Dataypte

• Strings are discussed in chapters 2 and three.
• Some string specifics
  • A string is a collection of 0 or more characters.

  • #include <string> 

    • gcc does not seem to require this, but it is good to include it.
  • It is part of the standard template library, but you may use strings and their member functions unless explicitly forbidden.
  • If you don't use using namespace std; all the use of string needs to be proceeded by sdt::, for example std::string word
    • More on this later.
    • But you may see it as you look at other code.
  • When a string variable is declared, it is set to the empty string or "".
  • Strings have many member functions
    • size() or length() gives the number of characters.
    • + is string concatenation, used to combine strings.
    • [i] or at(i) can be used to access individual characters
      • The value for i above must be between 0 and the size of the string -1.
      • Letters are numbered from 0.
    • find will search the string for a substring.
      • It will either return the position of the substring, a size_t
      • or the constant string::npos
      • rfind will search from the end.
    • substr(start, len) will extract a substring from the string
      • starting at position start, a size_t
      • For len letters
      • If len not supplied, it will go to the end of the string.
      • If len is longer than the remaining characters, it is not a problem.
• There are two c libraries that provide additional character manipulation functions
  • is* family
    • man isascii
    • These are old so they take an int and return an int
    • But they really take a char and return a bool
      • You might need to cast to eliminate compiler warnings.
    • They are useful when you want to identify different characteristics of a character.
  • to* family
    • man toupper
    • These take an int and return an int.
    • But really take a char and return a char
    • Again you may need to cast.
    • toupper only works on characters, NOT ON ENTIRE STRINGS.
• look at stringDemo.cpp