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Linux c括号作用域【原创笔记】

大师指点后,所做的笔记,很感谢一起愿意研究技术的同事,以下不是本人原创,是他分析的成果

#include <stdio.h>#include <time.h>struct lock_class_key { int ck;};#define mutex_init() do { static struct lock_class_key __key; static int a; printf("macro==>>Line=%d,&__key=0x%p &a=0x%p\n", __LINE__, &__key, &a); } while (0)void __mutex_init(){ do { static struct lock_class_key __key1; static int a1; printf("function==>>Line=%d,&__key1=0x%p &a1=0x%p\n", __LINE__, &__key1, &a1); } while (0); }int main(void){//do { static struct lock_class_key __key; static int a; printf("macro==>>Line=%d,&__key=0x%p &a=0x%p\n", 28, &__key, &a); } while (0);===>宏展开就是这样的,gcc -E -o test.i test.c//do { static struct lock_class_key __key; static int a; printf("macro==>>Line=%d,&__key=0x%p &a=0x%p\n", 29, &__key, &a); } while (0);//{ static struct lock_class_key __key; static int a; printf("macro==>>Line=%d,&__key=0x%p &a=0x%p\n", 28, &__key, &a); }//{ static struct lock_class_key __key; static int a; printf("macro==>>Line=%d,&__key=0x%p &a=0x%p\n", 29, &__key, &a); } {static int b1;} //=======>这种括号是作用域,一个函数名本来只有一个作用域,但是如果函数里面加了这种,相当于是在两个作用域里面,是允许这样定义的,地址也会不同//printf("fuck!!\n"); {static int b1;} mutex_init(); mutex_init(); __mutex_init(); __mutex_init(); return (0);}执行结果:macro==>>Line=37,&__key=0x0x60104c &a=0x0x601050macro==>>Line=38,&__key=0x0x601054 &a=0x0x601058function==>>Line=21,&__key1=0x0x601044 &a1=0x0x601048function==>>Line=21,&__key1=0x0x601044 &a1=0x0x601048

 

Linux c括号作用域【原创笔记】