新手，老提示else without a previous if的错误，还有为什么main函数前加void就错了，求大神指点
#include<stdio.h>#include<stdlib.h>
int main()
{char a,b,c;
printf("please input a letter\n",c);
c=getchar();
if(c>='a'&&c<='z')
{
a=c-32;
printf("%c-->%c\n",c,a);
}
else if (c>='A'&&c<='Z');
{
a=c+32;
printf("%c-->%c\n",c,a);
}
else
printf("please input a letter\n");
system("pause");
}
