allascii.c

[詳解]

/*++
/* NAME
/*  allascii 3
/* SUMMARY
/*  predicate if string is all ASCII
/* SYNOPSIS
/*  #include <stringops.h>
/*
/*  int allascii(buffer)
/*  const char *buffer;
/*
/*  int allascii_len(buffer, len)
/*  const char *buffer;
/*  ssize_t len;
/* DESCRIPTION
/*  allascii() determines if its argument is an all-ASCII string.
/*
/*  Arguments:
/* .IP buffer
/*  The null-terminated input string.
/* .IP len
/*  The string length, -1 to determine the length dynamically.
/* 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
/*
/*  Wietse Venema
/*  Google, Inc.
/*  111 8th Avenue
/*  New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <ctype.h>
#include <string.h>

/* Utility library. */

#include "stringops.h"

/* allascii_len - return true if string is all ASCII */

int     allascii_len(const char *string, ssize_t len)
{
    const char *cp;
    int     ch;

    if (len < 0)
    len = strlen(string);
    if (len == 0)
    return (0);
    for (cp = string; cp < string + len
     && (ch = *(unsigned char *) cp) != 0; cp++)
    if (!ISASCII(ch))
        return (0);
    return (1);
}