Print the ASCII Set

Printing the ASCII codes to the screen.
cpp code

/*
 * This program prints out a table of the ascii character values.
 */
#include <stdio.h>
#include <ctype.h>

int main() 
{
        int code;               /* Ascii value. */

        for(code = 0; code < 128; ++code) {
                /* Print the code and the character itself. */
                printf("%3d ", code);
                if(isspace(code)) 
                        printf(" ");
                else if(isprint(code))
                        printf("%c", code);
                else
                        printf(" ");

                /* If any of the interesting categories match, print it. */
                if(code == '\n')
                        printf(" (newline, \\n)\n");
                else if(code == ' ')
                        printf(" (space)\n");
                else if(code == '\t')
                        printf(" (tab, \\t)\n");
                else if(isspace(code))
                        printf(" (blank character)\n");
                else if(iscntrl(code))
                        printf(" (control character)\n");
                else if(isupper(code))
                        printf(" (capitol of %c)\n", tolower(code));
                else if(islower(code))
                        printf(" (lower case of %c)\n", toupper(code));
                else if(isdigit(code))
                        printf(" (digit)\n", toupper(code));
                else
                        putchar('\n');
        }
}

In the first printf, the construct %3d is the same as %d, except that printf is instructed to use at least three spaces to represent the number, padding with spaces at the left if necessary. (Use %-3d if you want the padding on the right.) This just keeps the output nicely aligned.

Notice how the integer value code is printed both with %d to get the integer value, and with %c to get the character itself. This works equally well if the variable is declared as char: it can be printed with either %d or %c.