What are Digraphs and How are They Used in C and C ?

Digraphs in C and C

Digraphs are two-character sequences that represent special characters in the C and C programming languages. They were introduced in C99 to provide compatibility with older systems that did not support the full ISO 646 character set.

The following digraphs are supported in C and C :

• %% represents #
• %? represents [
• ?> represents ]
• ?< represents {
• ?> represents }
• ?! represents |
• ^& represents ^
• :~ represents ~

These digraphs allow programmers to use these special characters even if they do not have a keyboard that supports them. For example, the following code is valid C and C :

<code class="c">#include <stdio.h>

#ifndef BUFSIZE
#define BUFSIZE  512
#endif

void copy(char d<::>, const char s<::>, int len)
{
    while (len-- >= 0)
    {
        d<:len:> = s<:len:>;
    }
}</code>

The digraph <::> is used to represent the # character, which is necessary for preprocessor directives.

The above is the detailed content of What are Digraphs and How are They Used in C and C ?. For more information, please follow other related articles on the PHP Chinese website!