C-Style Strings

• C Strings
  • Making C strings available in your programs
    • There is nothing to include, C Strings (also known as character arrays) are a built-in part of the C++ language.
    • Declaration Examples:
      • char myString1[]     = "This is a string"; // just big enough to hold the string value
      • char myString2[80] = "This string has enough space for 80 characters";
      • char myString3[40];     // this string has space for forty characters, but they are not initialized
  • Conceptual View:  While we think of a C++ string as having two parts (contents and length), a C string has only the contents, the length is implicitly defined by where the first NULL character (e.g., '\0') appears.
  • Input
    • Via an input stream
      • By default "white space" terminates the input of a string
      • Example
        • Given the code:

          char name[20];
          cout << "What is your name: ";
          cin   >> name;
          
          Suppose the user of the program types: "Joe Cool"

        • The string name would get assigned the first name (i.e., "Joe") only, because the last name is separated from the first by a space.
    • Via assignment
      • C Strings cannot be assigned as other fundamental objects
      • Example: Assuming name is decalred as above, the following assignment is illegal
        • name = "Skippy";
      • C Strings are assigned and compared using pre-defined functions
        • Assignment:  strcpy(name, "Skippy");   // accomplishes the assignment above
        • Comparison: strcmp(name, "Spunky"); // used in place of name == "Spunky"
  • Examples
    • Examples of various C string pre-defined functions:  cstring.cpp