6 枚举

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李延 LV6 2022-06-07

悬赏：20积分

# 1 枚举

枚举会在编译时将其直接编译为对应的值。

```c
#include <stdio.h>

enum DAY
{
    MON=1, TUE, WED, THU, FRI, SAT, SUN
};

int print( enum DAY day){
    printf("%d\n",day);
    return 0;
}

int main()
{
    enum DAY day;
    print(WED);
    return 0;
}
```

```asm
    .file  "enum.c"
   .section   .rodata.str1.1,"aMS",@progbits,1
.LC0:
   .string    "%d\n"
   .text
   .globl print
   .type  print, @function
print:
.LFB11:
   .cfi_startproc
   subq   $8, %rsp
   .cfi_def_cfa_offset 16
   movl   %edi, %esi
   movl   $.LC0, %edi
   movl   $0, %eax
   call   printf
   movl   $0, %eax
   addq   $8, %rsp
   .cfi_def_cfa_offset 8
   ret
   .cfi_endproc
.LFE11:
   .size  print, .-print
   .globl main
   .type  main, @function
main:
.LFB12:
   .cfi_startproc
   subq   $8, %rsp
   .cfi_def_cfa_offset 16
   movl   $3, %edi
   call   print
   movl   $0, %eax
   addq   $8, %rsp
   .cfi_def_cfa_offset 8
   ret
   .cfi_endproc
.LFE12:
   .size  main, .-main
   .ident "GCC: (GNU) 4.8.5 20150623 (Red Hat 4.8.5-44)"
   .section   .note.GNU-stack,"",@progbits
```

我们看到，在调用print函数时，是直接传的3

```asm
   movl   $3, %edi
```

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