选自论坛:http://bbs.csdn.net/topics/370070922
1.不用局部变量和全局变量实现strlen;
2.有2数据,写一个交换数据的宏;
先自己思考:
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1解答:
size_t
strlen
(
const
char
*str)
{
return
*str==0 ? 0 : 1+
strlen
(str+1);
}
PS:附strlen源码解析:http://blog.csdn.net/dw903632958/article/details/8929934
2解答:
赵老师神作@zhao4zhong1
#include <stdio.h> #define SWAP(a,b) ((&(a))!=(&(b)))?((a)^=(b)^=(a)^=(b)):((a)=(a)) char c1=1 ,c2=2 ; short s1=1 ,s2=2 ; int i1=1 ,i2=2 ; __int64 I1=1i64,I2=2i64; float f1=1.0f,f2=2.0f; double d1=1.0 ,d2=2.0 ; void main() { SWAP(c1,c2); printf("char %5d, %5d\n",c1,c2); SWAP(s1,s2); printf("short %5d, %5d\n",s1,s2); SWAP(i1,i2); printf("int %5d, %5d\n",i1,i2); SWAP(I1,I2); printf("__int64 %5I64d,%5I64d\n",I1,I2); SWAP(*(int *)&f1,*(int *)&f2);printf("float %5g, %5g\n",f1,f2); SWAP(*(__int64 *)&d1,*(__int64 *)&d2);printf("double %5lg, %5lg\n",d1,d2); SWAP(c1,c1); printf("%d\n",c1); } //char 2, 1 //short 2, 1 //int 2, 1 //__int64 2, 1 //float 2, 1 //double 2, 1 //2