A Java variable of type char can hold any 16-bit Unicode character. In C, the char type can represent any character in a character set that depends on the type of system or platform for which the program is compiled. This is usually a variation of US ASCII, but it doesn't have to be, so beware. In particular, it could be a multibyte encoding, where a larger set of characters are represented by several char objects, e.g. UTF-8. A basic set of characters, however, are always represented as single chars.

Java strings are objects of class String or StringBuilder, and represent sequences of char.

Strings in C are just arrays of, or pointers to, char, and don't exist as a formal type. Functions which handle strings typically assume that the string is terminated with a null character '\0', rather than being passed length parameter. A character array can be initialised like other arrays:

char word[] = { 'H', 'e', 'l', 'l', 'o', '!', '\0' };
char another[] = "Hello!";

Note that the second initialiser is a shorter form of the first, including the terminating null character. Such a string literal can also appear in an expression. It evaluates to a pointer to the first character.

const char *ptr;

ptr = "Hello!";

ptr now points to an anonymous, statically allocated array of characters. Attempting to write to a string literal like this has undefined behaviour, so the use of const ensures that such attempts are detected while compiling.

Utilities for handling character strings are declared in <string.h>. For example, the function to copy a string from one place to another is declared as:

char *strcpy(char *to, const char *from);

…and may be used like this:

#include <string.h>

char words[100];

strcpy(words, "Madam, I'm Adam.");

Like many of the other <string.h> functions, strcpy assumes that you have already allocated sufficient space to store the string.