使用指針，實現一個數組的倒敘

#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
    char *p,a[100],b[100];
    int len,i;

    p = a;
    printf("Please input a string:\n");
    gets(a);
    puts(a);

    len = strlen(a);
    p = p + len -1;

    for(i = 0; i < len; i++)
    {
        b[i] = *p;
        p--;
    }

    b[i] = '\0';
    puts(b);

    return 0;
} 

使用指針，實現字符串的壓縮aaaabbbd --> a4b3d

#include <stdio.h>

int main(int argc, char *argv[])
{
    char a[100] = {0};
    char b[100] = {0};
    char *p = a;
    char *q = b;
    int i = 1;

    gets(a);

    while(*p)
    {
        if(*p == *(p + 1))
            i++;
        else
        {
            if(i != 1)
            {
                if(i < 10)
                {
                    *q++ = *p;
                    *q++ = i + 48;
                    i = 1;
                }
                else if(i >= 10 && i < 100)
                {
                    *q++ = *p;
                    *q++ = i / 10 + 48;
                    *q++ = i % 10 + 48;
                    i = 1;
                }
            }
            else
                *q++ = *p;
        }

        p++;
    }
    //*q = '\0';
    puts(b);


    return 0;
}