omg.c

omg.c

#include <stdio.h>

/* $ ./a.out Erin

// registers (stored on the CPU)
stack pointer:   0x02
base pointer:    0x00
program counter: 0043

// "the stack" ("working" memory, ie for a given function)
0 | 0002  <-- argc \
1 | 1000  <-- argv /
2 | 0043  <-- return to here
3 | 0000  <-- old base pointer
4 | 1020  <-- "num args: %d\n"
5 | 0002  <-- argc
6 | 0000

...

// "the heap" (memory that sticks around)
1000 | 1002 \ <-- argv
1001 | 1010 /
1002 | 0046 <-- '.'
1... | 0047 <-- '/'
1... | 0097 <-- 'a'
1... | 0046 <-- '.'
1... | 0111 <-- 'o'
1... | 0117 <-- 'u'
1... | 0116 <-- 't'
1010 | 0069 <-- 'E'
1... | 0114 <-- 'r'
1... | 0105 <-- 'i'
1... | 0110 <-- 'n'
*/


/* 0x1010 has 0069 ('E'), a char */
/* 0x1001 has 1010,       a char* */
/* 0x0001 has 1000,       a char** */

int main(int argc, char** argv) {
  printf("num args: %d\n", argc);

  int i;
  for(i = 0; i < argc; ++i) {
    char* s1 = argv[i];
    char* s2 = *(argv + i);
    printf("arg %d: %s\n", i, s1);
    printf("       %s\n", s2);
  }

  return 0;
}