把输入一次一个字符复制到输出

# include <stdio.h>
void main ()
{
    int c;
    while ((c=getchar())!=EOF)
        putchar(c);
//printf("hello world!\c");
}

EOF的是为-1

# include <stdio.h>
void main ()
{
    int c;
    c=getchar();
    while (c !=EOF)
    {
        putchar(c);
        c=getchar();
    }

}