将char指针转换为unsigned char数组

Question

I want to convert a char pointer to a unsigned char var, I thought I could do that with just casting but it doesn't work:

char * pch2;
//Code that puts something in pc2
part1 = (unsigned char) pch2;

I've the code to this:

result.part1 = (unsigned char *) pch2;
printf("STRUCT %s\n",result.part1);

result is just a struct with unsigned char arrays.

EDIT:

            pch2 = strtok( ip, "." );

            while( pch2 != NULL ){
                printf( "x %d x: %s\n", i, pch2 );
                pch2[size-1] = '\0';

                if(i == 1)
                    result.part1 = (unsigned char *) pch2;
                if(i == 2)
                    result.part2 = (unsigned char *) pch2;
                if(i == 3)
                    result.part3 = (unsigned char *) pch2;
                if(i == 4)
                    result.part4 = (unsigned char *) pch2;
                i++;
                pch2 = strtok (NULL,".");
            }   
            printf("STRUCT %c\n",result.part1);

Struct:

typedef struct
{
    unsigned char part1;
    unsigned char part2;
    unsigned char part3;
    unsigned char part4;
} res;

Answer 1

you cast to unsigned char not unsigned char* you forgot the *

part1 = (unsigned char*) pch2;

if pch2 is not null terminated the program will crash, if you're lucky, when you use strlen , so you need to null terminate it first before printing using pch2 , try this instead:

pch2[size-1] = '\0';  /* note single quote */
result.part1 = (unsigned char *) pch2;

Update: define your structure like so:

typedef struct
{
    const char *part1;
    const char *part2
    const char *part3;
    const char *part4;
} res;

And assign to it without casting at all:

result.part1 = pch2;

Answer 2

You want to do this:

part1 = (unsigned char*) pch2;

Instead of:

part1 = (unsigned char) pch2;

Answer 3

Try something like this:-

 char *ph2;
 unsigned char *new_pointer = (unsigned char*) ph2;

Answer 4

I want to convert a char pointer to a unsigned char var

Are you sure? Converting pointer to char to unsigned char is not going to do any good - value will get truncated to 1 byte, and it will be meaningless anyway. Maybe you want to dereference a pointer and get value pointed by it - then you should do something like this:

unsigned char part1 = (unsigned char)*pch2;

After your edit I see that part1 is character array - if your program crashes after it is used, you probably fill pch2 incorrectly. Maybe you forgot '\\0' terminator?

EDIT:

You see, it is much better now to answer your question having all required information. Do you need to use strtok ? Would this be good?

    res result;
    char* ip = "123.23.56.33";

    sscanf(ip, "%hhu.%hhu.%hhu.%hhu", &result.part1, &result.part2, &result.part3, &result.part4);

Answer 5

Found the problem, forgot to cast the char pch2 to unsigned int and then I can printout with %u. Code:

unsigned int temp;

temp = atoi(pch2);

result.part1 = temp;
printf("Struct: %u\n",result.part1);

Thanks for your help guys!