程序代码：

#include<stdio.h>
main()
{
    char *str1="Dot saw I was tod";
    char *str2="Niagara O roar again!";
    printf("the palindromen:\n");
    if(hw(str1)>0)
    printf("\n%s",str1);
    if(hw(str2)>0)
    printf("\n%s",str2);
    getch();
}
int hw(char *string)
{
    int i,n,m,s,len=0;
    for(i=0;string[i]!='\0';i++)
    {
        len++;
    }
    n=0;
    m=len-1;
    while(n<m)
    {
       if(string[n]>=65&&string[n]<=90||string[n]>=97&&string[n]<=122)
        {if(string[n]>=65&&string[n]<=90)
          string[n]=string[n]+32;
        }
        else {n++;
        continue;
        }
       if(string[m]>=65&&string[m]<=90||string[m]>=97&&string[m]<=122)
        {
            if(string[m]>=65&&string[m<=90])
            string[m]=string[m]+32;
        }
        else {m--;
        continue;
        }
        if(string[n]!=string[m])
        {
            s=-1;
            return s;
            break;
        }
    }