输入一串字符串，将其逆向输出

#include<stdio.h>
int main(void)
{
char m,str[100];
int i, j;
printf("Please input a string:\n");
scanf("%s",str);
printf("The origal string  into:%s\n", str);
for (i = 0; str[i] != '\0'; i++)
for (j = i + 1;str[j] != '\0'; j++)
{
m = str[i];
str[i] = str[j];
str[j] = m;
}
printf("The string changs into:%s\n", str);
return 0;
}

#include <stdio.h>
int main()
{
char s[100];
char *p;
int i;

p=s;
scanf("%s",s);
for (i=0; p[i]!='\0'; i++)
{

}
for (i--; i>=0; i--)
{
printf("%c",p[i]);
}
}