balpar.c

[詳解]

/*++
/* NAME
/*  balpar 3
/* SUMMARY
/*  determine length of string in parentheses
/* SYNOPSIS
/*  #include <stringops.h>
/*
/*  size_t  balpar(string, parens)
/*  const char *string;
/*  const char *parens;
/* DESCRIPTION
/*  balpar() determines the length of a string enclosed in 
/*  the specified parentheses, zero in case of error.
/* SEE ALSO
/*  A balpar() routine appears in Brian W. Kernighan, P.J. Plauger:
/*  "Software Tools", Addison-Wesley 1976. This function is different.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include <sys_defs.h>

/* Utility library. */

#include <stringops.h>

/* balpar - return length of {text} */

size_t  balpar(const char *string, const char *parens)
{
    const char *cp;
    int     level;
    int     ch;

    if (*string != parens[0])
    return (0);
    for (level = 1, cp = string + 1; (ch = *cp) != 0; cp++) {
    if (ch == parens[1]) {
        if (--level == 0)
        return (cp - string + 1);
    } else if (ch == parens[0]) {
        level++;
    }
    }
    return (0);
}