My code below gave a different length for the unsigned char pointer I expect. I thought I should be getting 12 (or 13) or 0 (or 1) for pph and pphChar. What is my problem? I got different results for length and oneLength each time, when I repeat the run.
How can I get the length of pph?
Do I need to put a '\n' at the end to determine the length?
I use VS2010, XP and C++.
#include "stdafx.h"
#include <stdlib.h>
#include <Windows.h>
#include <stdio.h>
#include <tchar.h>
typedef unsigned char uint8_t;
int _tmain(int argc, _TCHAR* argv[])
{
int length;
int len = 13;
uint8_t *phh;
char * phhChar;
printf("assigned mem %d\n", sizeof(unsigned char)*len);
phh = (unsigned char *) malloc(sizeof(unsigned char)*len);
phhChar = (char *) malloc(sizeof(char)*len);
phh[0] = (unsigned char) '1';
phh[1] = (unsigned char) '2';
phh[2] = (unsigned char) '3';
phh[3] = (unsigned char) '4';
phh[4] = (unsigned char) '5';
phh[5] = (unsigned char) '6';
phh[6] = (unsigned char) '7';
phh[7] = (unsigned char) '8';
phh[8] = (unsigned char) '9';
phh[9] = (unsigned char) '0';
phh[10] = (unsigned char) '1';
phh[11] = (unsigned char) '2';
phh[12] = (unsigned char) '\n';
phhChar[0] = (char) '\n';
printf("size of char %d\n", sizeof(unsigned char));
length = strlen((const char*)phh);
int oneLength = strlen((const char*)phhChar);
printf("len %d\n", length );
printf("onelebgth %d\n", oneLength);
OUTPUT
assigned mem 13
size of char 1
len 32 - different each time
oneLength 32 - different each time
You are missing the null terminator \0 at the end of the string so strlen is not able to know where the unsigned char * ends.
Actually it keeps counting after the address to last character you set by looking until it reaches a \0.