新学 C++ 问个问题

simhgd

以下程序 在Windows2k3下写的 内容就是想在屏幕顶部中央 显示copyright的内容
编译通过 但是 运行时
出现
1.exe -Application Error

The instruction at "0x77bd6f33" referenced memory at "0x00000020". The memory could not be "read".



/*-------------------------程序-------------------------------*/
#include <iostream.h>
#include <string.h>
#define line_max 80
char *copyright;
char *return_copyright(char *copyright)
{
    int i;
    int line_start2char_start;
    char *tmp;
    line_start2char_start=line_max-strlen(copyright)/2;
    for(i=1;i<=line_start2char_start;i++)
    {
        strcat(tmp,(char *)32);
    }
    strcat(copyright,tmp);
    return tmp;
}
int main()
{
    copyright="Sim Studio";
    cout<<return_copyright(copyright)<<endl;
}

好心人帮我看看 错在什么地方~  谢谢啦~~

ideawu

tmp指针赋值吗？

http://www.cplusplus.com/ref/ 的例子：

2. char *  strcat ( char * dest, const char * src );
4. Append string.
5.   Appends src string to dest string. The terminating null character in dest is overwritten by the first
6. character of src. The resulting string includes a null-character at end.
8. Parameters.
10. dest
11.     Pointer to a null-terminated string with [b]enough space allocated to contain both src and dest.[/b]
12. src
13.     Null-terminated string to append.
15. Return Value.
16.   dest is returned.
18. Portability.
19.   Defined in ANSI-C.
21. Example.
23. /* strcat example */
24. #include <stdio.h>
25. #include <string.h>
27. int main ()
28. {
29.   char str[80];
30.   strcpy (str,"strings  ");
31.   strcat (str,"have been ");
32.   strcat (str,"concatenated.");
33.   puts (str);
34.   return 0;
35. }
37. Output:
38. strings have been concatenated.

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