String length without strlen, printf and sizeof

gistfile1.cpp

#include <stdio.h>

typedef void (*fptr)(char* pString, int* pLen);

void istringlength(char* pString, int* pLen);
void pstringlength(char* pString, int* pLen);

fptr pFunc[2] = {istringlength, pstringlength};

void istringlength(char* pString, int* pLen) {
     int nFactor = !(!(*pString));
     *pLen += nFactor;
     pFunc[!nFactor](pString+1, pLen);
     return;
}

void pstringlength(char* pString, int* pLen) {
    return;
}

int main () {
    int nLen = 0;
    istringlength("Hello World", &nLen);
    printf("%d\n", nLen);
    return 0;
}