user: Demonstrate the C code that generates the assembly output below:

```asm
<Getop>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %rdi,%rbx
  sub    $0x18,%rsp
  nopl   (%rax)
L168:
  xor    %eax,%eax
  call   <getch@plt>
  mov    %al,(%rbx)
  mov    %eax,%r12d
  cmp    $0x20,%al
  je     L168
  cmp    $0x9,%eax
  je     L168
  movb   $0x0,0x1(%rbx)
  movsbl %al,%ebp
  mov    %ebp,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L235
  mov    %rbx,%rbp
  jmp    L178
  nopl   (%rax)
L138:
  xor    %eax,%eax
  call   <getch@plt>
  mov    %eax,%r12d
L178:
  mov    %r12b,0x0(%rbp)
  movsbl %r12b,%edi
  mov    %rbp,%rbx
  add    $0x1,%rbp
  call   <isalpha@plt>
  test   %rax,%rax
  jne    L138
  mov    D15(%rip),%rax
  movb   $0x0,(%rbx)
  cmp    %r12d,(%rax)
  jne    L66
  mov    $0x1,%r12d
L11:
  add    $0x18,%rsp
  mov    %r12d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L66:
  mov    %r12d,%edi
  mov    $0x1,%r12d
  call   <unGetch@plt>
  jmp    L11
  nopl   0x0(%rax,%rax,1)
L235:
  mov    %ebp,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L73
  lea    -0x2d(%r12),%eax
  cmp    $0x1,%eax
  jbe    L73
  cmp    $0x3d,%r12d
  je     L86
  test   %r12d,%r12d
  mov    $0x2,%eax
  cmove  %eax,%r12d
  jmp    L11
  xchg   %ax,%ax
L73:
  xor    %eax,%eax
  cmp    $0x2d,%r12d
  je     L57
  call   <getch@plt>
  mov    %eax,%ebp
  movsbl %al,%edi
L31:
  mov    %ebx,%r15d
  lea    0x1(%rbx),%r12
  neg    %r15d
  jmp    L155
  xchg   %ax,%ax
L226:
  xor    %eax,%eax
  call   <getch@plt>
  mov    %eax,%ebp
  movsbl %al,%edi
L155:
  mov    %bpl,(%r12)
  lea    (%r15,%r12,1),%r14d
  mov    %r12,%r13
  add    $0x1,%r12
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L226
  cmp    $0x2e,%ebp
  je     L112
L43:
  mov    D15(%rip),%rax
  movb   $0x0,0x0(%r13)
  xor    %r12d,%r12d
  cmp    %ebp,(%rax)
  je     L11
  mov    %ebp,%edi
  call   <unGetch@plt>
  jmp    L11
L57:
  call   <getch@plt>
  movsbl %al,%edi
  mov    %eax,%ebp
  mov    %edi,0xc(%rsp)
  call   <isdigit@plt>
  mov    0xc(%rsp),%edi
  test   %rax,%rax
  jne    L31
  cmp    $0x2e,%ebp
  je     L31
  jmp    L11
L112:
  movslq %r14d,%r14
  lea    0x1(%rbx,%r14,1),%rbx
  nopl   0x0(%rax,%rax,1)
L110:
  xor    %eax,%eax
  mov    %rbx,%r13
  add    $0x1,%rbx
  call   <getch@plt>
  mov    %al,-0x1(%rbx)
  movsbl %al,%edi
  mov    %eax,%ebp
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L110
  jmp    L43
L86:
  xor    %eax,%eax
  call   <getch@plt>
  cmp    $0xa,%eax
  jne    L11
  xor    %edi,%edi
  call   <unGetch@plt>
  jmp    L11
```

assistant: ```c
int Getop(char s[]) {
  int i = 0;
  int c;
  int next;
  while ((s[0] = c = getch()) == ' ' || c == '\t') {
    ;
  }
  s[1] = '\0';
  if (isalpha(c)) {
    i = 0;
    while (isalpha(s[i++] = c)) {
      c = getch();
    }
    s[i - 1] = '\0';
    if (c != EOF)
      unGetch(c);
    return 1;
  }
  if (!isdigit(c) && c != '.' && c != '-') {
    if ('=' == c && '\n' == (next = getch())) {
      unGetch('\0');
      return c;
    }
    if ('\0' == c)
      return 2;
    return c;
  }
  if (c == '-') {
    next = getch();
    if (!isdigit(next) && next != '.') {
      return c;
    }
    c = next;
  } else {
    c = getch();
  }
  while (isdigit(s[++i] = c)) {
    c = getch();
  }
  if (c == '.') {
    while (isdigit(s[++i] = c = getch()))
      ;
  }
  s[i] = '\0';
  if (c != EOF)
    unGetch(c);
  return 0;
}
```