C++ inline & static

Sun, 17 May 2026 00:00:00 +0800

inline
#

内联展开
#

以下面这段代码为例：

const char* num_check(int v) {
 return (v % 2 > 0) ? "奇" : "偶";
}

int main() {
 for (int i = 0; i <= 99; i++)
 printf("%02d %s\n", i, num_check(i));
}

未开启优化时编译，可以看到 num_check 是正常的函数调用（call num_check(int)）：

.LC0:
 .string "\345\245\207"
.LC1:
 .string "\345\201\266"
num_check(int):
 push rbp
 mov rbp, rsp
 mov DWORD PTR [rbp-4], edi
 mov edx, DWORD PTR [rbp-4]
 mov eax, edx
 sar eax, 31
 shr eax, 31
 add edx, eax
 and edx, 1
 sub edx, eax
 mov eax, edx
 test eax, eax
 jle .L2
 mov eax, OFFSET FLAT:.LC0
 jmp .L4
.L2:
 mov eax, OFFSET FLAT:.LC1
.L4:
 pop rbp
 ret
.LC2:
 .string "%02d %s\n"
main:
 push rbp
 mov rbp, rsp
 sub rsp, 16
 mov DWORD PTR [rbp-4], 0
 jmp .L6
.L7:
 mov eax, DWORD PTR [rbp-4]
 mov edi, eax
 call num_check(int)
 mov rdx, rax
 mov eax, DWORD PTR [rbp-4]
 mov esi, eax
 mov edi, OFFSET FLAT:.LC2
 mov eax, 0
 call printf
 add DWORD PTR [rbp-4], 1
.L6:
 cmp DWORD PTR [rbp-4], 99
 jle .L7
 mov eax, 0
 leave
 ret

开启 -O1 后编译器会自动将函数内联展开，消除函数调用开销：

C++ on Nanmonk's Blog

C++ inline & static

inline #

内联展开 #

inline
#

内联展开
#