@小帅讲嵌入式：字符串倒置
#include<stdlib.h>
int main(int argc, char const *argv[])
{
char buf[32]="hello";
char t;
int n,i;
for(n=0;buf[n] != '\0';n++);//n==5,实际个数

for(i=0;i<n/2;i++)//交换n/2次
{
t = buf[i];
buf[i] = buf[n-1-i];
buf[n-1-i] = t;
}
printf("%s\n",buf);

return 0;
}