The C++Course provides a general introduction to programming in C++. It is based on A.B. Downey's book, How to Think Like a Computer Scientist. Click here for details.

Extracting Characters from a String

Strings are called "strings" because they are made up of a sequence, or string, of characters. The first operation we are going to perform on a string is to extract one of the characters. C++ uses square brackets ([ and ]) for this operation:

  pstring fruit = "banana";
  char letter = fruit[1];
  cout << letter << endl;

The expression fruit[1] indicates that I want character number 1 from the string named fruit. The result is stored in a char named letter. When I output the value of letter, I get a surprise:


a is not the first letter of "banana". Unless you are a computer scientist. For perverse reasons, computer scientists always start counting from zero. The 0th letter ("zeroeth") of "banana" is b. The 1th letter ("oneth") is a and the 2th ("twoeth") letter is n.

If you want the the zereoth letter of a string, you have to put zero in the square brackets:

  char letter = fruit[0];

Last Update: 2005-12-05