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| -rw-r--r-- | strstr.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/strstr.c b/strstr.c new file mode 100644 index 00000000..5b80fe43 --- /dev/null +++ b/strstr.c @@ -0,0 +1,70 @@ +/* + * strstr.c -- return the offset of one string within another. + * + * Copyright (C) 1997 Free Software Foundation, Inc. + * + * This program is free software; you can redistribute it and/or modify it under + * the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2, or (at your option) any later + * version. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program; if not, write to the Free Software Foundation, Inc., 59 + * Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + +/* Written by Philippe De Muyter <phdm@info.ucl.ac.be>. */ + +/* + * NAME + * + * strstr -- locate first occurence of a substring + * + * SYNOPSIS + * + * char *strstr (char *s1, char *s2) + * + * DESCRIPTION + * + * Locates the first occurence in the string pointed to by S1 of the string + * pointed to by S2. Returns a pointer to the substring found, or a NULL + * pointer if not found. If S2 points to a string with zero length, the + * function returns S1. + * + * BUGS + * + */ + +char * +strstr (buf, sub) + register char *buf; + register char *sub; +{ + register char *bp; + + if (!*sub) + return buf; + for (;;) + { + if (!*buf) + break; + bp = buf; + for (;;) + { + if (!*sub) + return buf; + if (*bp++ != *sub++) + break; + } + sub -= (unsigned long) bp; + sub += (unsigned long) buf; + buf += 1; + } + return 0; +} + |