Pascal String to cstring

Question

Trying to write a simple pascal to cstring conversion method. The method takes a void* ptr to the pascal string. The resulting cstring returns the correct number of characters for the pascal string that gets passed. But all it contains is the hex value for the length of the string. For instance, a pascal strings first element is the length of the string. So if the number in the first element is 15, for instance, the return statement is returning a cstring with 15 characters all set to FF. its as though the pointer isn't being incremented. Not sure how to fix this. Any help would be appreciated.

#include <stdio.h>
#include <stdlib.h>

char* pascal_convert(void* ptr) {
int len = *((int*)ptr)+1;
char *cString = malloc(sizeof(char) * (len));
(int*)ptr + 1;
for (int i = 0; i < len; i++) {
    cString[i] = *((char*)ptr);
    (char*)ptr + 1;
}
cString[len] = '\0';
return cString;

}

Adding : what size is your int ? what is your pascal string maximum size ? — dvhh
– dvhh, Commented Oct 24, 2016 at 4:21
the the value of the int is the value of the first element in the pascal string. There is no upper bound on the size of the pascal string. incrementing the cast pointer with ++ doesnt work. — Keith
– Keith, Commented Oct 24, 2016 at 4:32

Zamrony P. Juhara · Accepted Answer · 2016-10-24 04:21:30Z

1

You need to store current address of string somewhere

int currentPtr = (int*)ptr + 1;
for (int i = 0; i < len; i++) {
    cString[i] = *((char*) currentPtr);
    currentPtr++;
}

answered Oct 24, 2016 at 4:21

Zamrony P. Juhara

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2 Comments

Keith Over a year ago

This worked. Thank you. Would you mind explaining what I did wrong ?

Zamrony P. Juhara Over a year ago

Your code (char*)ptr + 1; increase the address but ptr value will stay the same.

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