最近想實現一下strlen, 寫了如下程式碼

int mystrlen(const char * str)
{
    assert(str != NULL);
    const char * pstr = str;

    //get length
    int length = 0;
    while (*pstr++ && ++length);
    //printf("length = %d, %d\n", length, strlen(str));

    return length;
}

本來以為已經是蠻簡潔的了， 結果一看標準庫， 發現更簡單<-_->!!!

/***
*strlen.c - contains strlen() routine
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       strlen returns the length of a null-terminated string,
*       not including the null byte itself.
*
**********************************************************************
 
*********/

#include <cruntime.h>
#include <string.h>

#pragma function(strlen)

/***
*strlen - return the length of a null-terminated string
*
*Purpose:
*       Finds the length in bytes of the given string, not including
*       the final null character.
*
*Entry:
*       const char * str - string whose length is to be computed
*
 
*Exit:
*       length of the string "str", exclusive of the final null byte
*
*Exceptions:
*
*******************************************************************************/

size_t __cdecl strlen (
        const char * str
        )
{
        const char *eos = str;

        while( *eos++ ) ;

        return( eos - str - 1 );
}

放在這裡算是一個記錄吧<^_^>