#include <stdio.h>
#define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

main()
{
    int len;
    int max;
    char line[MAXLINE];
    char longest[MAXLINE];

    max = 0;

    while ((len = getline(line, MAXLINE)) > 0)
    {
        if (len > max)
        {
            max = len;
            copy(longest, line);
        }

    if (max > 0)
    {
        printf("%s", longest);
    }
    return 0;
}

int getline(char s[], int lim)
{
    int c, i;

    for (i = 0; i < lim - 1 && (c = getchar()) != EOF && c != '\n'; ++i)
        s[i] = c;
    if (c == '\n')
    {
        s[i] = c;
        ++i;
    }
    s[i] = '\0';

    return i;
}

void copy(char to[], char from[])
{
    int i;

    i = 0;
   
    while ((to[i] = from[i]) !='\0')
        ++i;
}

--------------------Configuration: 1-7 - Win32 Debug--------------------
Compiling...
1-7.c
D:\C\1-7.c(31) : error C2143: syntax error : missing ';' before 'type'
D:\C\1-7.c(35) : error C2065: 'i' : undeclared identifier
D:\C\1-7.c(35) : error C2065: 'lim' : undeclared identifier
D:\C\1-7.c(35) : error C2065: 'c' : undeclared identifier
D:\C\1-7.c(36) : error C2065: 's' : undeclared identifier
D:\C\1-7.c(36) : error C2109: subscript requires array or pointer type
D:\C\1-7.c(36) : error C2106: '=' : left operand must be l-value
D:\C\1-7.c(39) : error C2109: subscript requires array or pointer type
D:\C\1-7.c(39) : error C2106: '=' : left operand must be l-value
D:\C\1-7.c(42) : error C2109: subscript requires array or pointer type
D:\C\1-7.c(42) : error C2106: '=' : left operand must be l-value
Error executing cl.exe.

1-7.obj - 11 error(s), 0 warning(s)

少了一個右花括號，還説照著打。不照著打，恐怕還不易錯。照著打，其實是不過腦的。

多谢，我是开始自己摸索着打，结果发现这个问题怎么改都不行，就照着打了一遍，还是太粗心。