.急求一道c语言编程题！！！

//---------------------------------------------------------------------------

#include
#include
#define change 0

int main(void)
{
char str[80];/*字符串长度最大为80（包括结束字符）*/
int i;
scanf("%79[^\n]",str);/*输入最多79个字符，用回车结尾*/
#if (change)
for (i = 0; str[i]; i++)
if (isalpha(str[i]))
if (str[i]=='z') putchar('a');
else if (str[i]=='Z') putchar('A');
else putchar(str[i]+1);
else putchar(str[i]);
#else
printf("%s\n",str);
#endif

return 0;
}
//---------------------------------------------------------------------------