Use only printable characters in text comparisions.

Declare (non)printable characters (nonprinting)

Variable declaration

Segment Source

 135: /* Table of non-printing characters. */
 136: static int nonprinting[UCHAR_LIM];
 137: 

Insert user message text

Text insertion

Segment Source

 226:   -i               consider only [\\040-\\0176] characters in keys\n\

Define (non)printable characters

Code insertion

Segment Source

 459:       if (!ISPRINT (i))
 460:         nonprinting[i] = 1;

Parse PrintOnly option (-i)

Code insertion

Segment Source

1688:         case 'i':
1689:           key->ignore = nonprinting;
1690:           break;