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Diffstat (limited to 'compat/strstr.c')
| -rw-r--r-- | compat/strstr.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/compat/strstr.c b/compat/strstr.c new file mode 100644 index 0000000..6698c9f --- /dev/null +++ b/compat/strstr.c @@ -0,0 +1,70 @@ +/* + * 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. + */ + +#include "tcl.h" +#ifndef NULL +#define NULL 0 +#endif + +/* + *---------------------------------------------------------------------- + * + * 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( + 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 NULL; +} |
