Logo Search packages:      
Sourcecode: tcl8.0 version File versions  Download package

strstr.c

/* 
 * strstr.c --
 *
 *    Source code for the "strstr" library routine.
 *
 * Copyright (c) 1988-1993 The Regents of the University of California.
 * Copyright (c) 1994 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: strstr.c,v 1.2 1998/09/14 18:39:45 stanton Exp $
 */

/*
 *----------------------------------------------------------------------
 *
 * strstr --
 *
 *    Locate the first instance of a substring in a string.
 *
 * Results:
 *    If string contains substring, the return value is the
 *    location of the first matching instance of substring
 *    in string.  If string doesn't contain substring, the
 *    return value is 0.  Matching is done on an exact
 *    character-for-character basis with no wildcards or special
 *    characters.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

char *
strstr(string, substring)
    register char *string;    /* String to search. */
    char *substring;          /* Substring to try to find in string. */
{
    register char *a, *b;

    /* First scan quickly through the two strings looking for a
     * single-character match.  When it's found, then compare the
     * rest of the substring.
     */

    b = substring;
    if (*b == 0) {
      return string;
    }
    for ( ; *string != 0; string += 1) {
      if (*string != *b) {
          continue;
      }
      a = string;
      while (1) {
          if (*b == 0) {
            return string;
          }
          if (*a++ != *b++) {
            break;
          }
      }
      b = substring;
    }
    return (char *) 0;
}

Generated by  Doxygen 1.6.0   Back to index