Demonstrating some of the interesting challenges in C programming. To clarify these concepts I referred to: http://www.geeksforgeeks.org/memory-layout-of-c-program/.

teststr.c

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

void printer(char *aString);
void printerX(char *aString);

int main(int argc, char *argv[]){
  char *simpleString = "Hello, World";

  printer(simpleString);

  return 0;
}

void printer(char *aString){
  printf("%s was passed in.\n", aString);
  printf("'%c' was at element 2\n", aString[2]);
  printf("'%c' was at element 10\n", *(aString + 10));

  /* This will not work and will cause a segfault */
  aString[2] = 'X';
}

void printerX(char *aString){
  int len = strlen(aString);
  char copy[len];

  strcpy(copy, aString);
  printf("saw a length of %i for clone '%s'\n", len, copy);
  copy[2] = 'X';
  *( copy + 3 ) = 'Y';
  printf("saw a length of %i for clone '%s'\n", len, copy);
}

using printer function

// Running `printer` function in main

➜  ex1 git:(master) ✗ ./teststr 
Hello, World was passed in.
'l' was at element 2
'l' was at element 10
[1]    29283 segmentation fault  ./teststr

Moving the initial string: simpleString to outside of main did not change things.

Hello, World was passed in.
'l' was at element 2
'l' was at element 10
[1]    29336 segmentation fault  ./teststr

Valgrind reports:

==29347== Memcheck, a memory error detector
==29347== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==29347== Using Valgrind-3.6.1-Debian and LibVEX; rerun with -h for copyright info
==29347== Command: ./teststr
==29347== 
Hello, World was passed in.
'l' was at element 2
'l' was at element 10
==29347== 
==29347== Process terminating with default action of signal 11 (SIGSEGV)
==29347==  Bad permissions for mapped region at address 0x8048632
==29347==    at 0x804848B: printer (teststr.c:22)
==29347==    by 0x8048429: main (teststr.c:11)
==29347== 
==29347== HEAP SUMMARY:
==29347==     in use at exit: 0 bytes in 0 blocks
==29347==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==29347== 
==29347== All heap blocks were freed -- no leaks are possible
==29347== 
==29347== For counts of detected and suppressed errors, rerun with: -v
==29347== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 11 from 6)
[1]    29347 segmentation fault  valgrind ./teststr

Using printerX function

saw a length of 12 for clone 'Hello, World'
saw a length of 12 for clone 'HeXYo, World'