Congratulations on completing the lesson on strings in C! You are now capable of solving many problems that require string manipulation. Here is a brief review of everything you learned:

  • In C, strings are simply arrays of the char data type.
  • Since strings are arrays, they are subject to all the properties and constraints of an array.
    • You cannot change the size of a string.
    • You cannot delete characters from a string; only replace them.
    • Modifying a character in a string is done in the same way as modifying an element in an array.
    • You can loop through a string like you would an array.
  • A string can be created in one of two ways:
    • The first being an array of chars: char str[] = {'S', 't', 'r', 'i', 'n', 'g', '\0'};
    • The second and more convenient is to use a string literal: char str[] = "String";
  • An empty string of length len, is created like so: char str[len];
  • All strings must end with the null terminating character ‘\0’.
    • This character must be added manually when creating a string using the array method.
    • This character is automatically added when creating a string using a string literal.
  • The length of a string is the number of characters it contains plus one to account for the null character.
  • There exists a library in the C language that contains common functions that are used to operate on strings. The library is imported by including the line #include<string.h> at the top of the code.
  • The strlen() function returns the number of characters in that string excluding the null terminator.
    • Syntax: strlen(str);
  • The strcat() function concatenates two strings together.
    • Syntax: strcat(dst, src);
    • strcat() creates a new string of length strlen(src) + strlen(dst) + 1, containing all the characters of strings dst and src. The new string is assigned to the variable holding the original dst string. A separate third string is NOT created.
  • The function strcpy(), copies an existing string into a new empty string.
    • The empty string must be long enough to accommodate the original string or else undefined behavior will occur. Good work!

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