strlen.c

来自「Many C samples. It is a good sample for 」· C语言 代码 · 共 38 行

/*  File   : strlen.c
    Author : Richard A. O'Keefe.
    Updated: 23 April 1984
    Defines: strlen()

    strlen(s) returns the number of characters in s, that is, the number
    of non-NUL characters found before the closing NULEosCh.  Note: some
    non-standard C compilers for 32-bit machines take int to be 16 bits,
    either put up with short strings or change int  to  long  throughout
    this package.  Better yet, BOYCOTT such shoddy compilers.
    Beware: the asm version works only if strlen(s) < 65536.
*/

#include "strings.h"

#if	VaxAsm

int strlen(s)
    char *s;
    {
	asm("locc  $0,$65535,*4(ap)");
	asm("subl3 r0,$65535,r0");
    }

#else  ~VaxAsm

int strlen(s)
    register char *s;
    {
	register int L;
	
	for (L = 0; *s++; L++) ;
	return L;
    }

#endif	VaxAsm