看看这三句话出了什么问题?

[Truman]

char szHead[10];
char szDst[256];

strcpy(szHead,"Head");
strcpy(szDst,"adfasdfasdfddfasdfasd");
sprintf(szDst,"%s\n%s",szHead,szDst);
本来想在szDst前加个头,可是结果却是szDst变成了"Head\nHead\nHead\n......

what's the problem of these statement?

[qing_li73]

char szHead[10];
char szDst[256];
char szTemp[256];


strcpy(szHead,"Head");
strcpy(szTemp,"adfasdfasdfddfasdfasd");
sprintf(szDst,"%s\n%s",szHead,szTemp);

[浪湾]

char szHead[10];
char szDst[256];
char szDst2[256];

strcpy(szHead,"Head");
strcpy(szDst2,"adfasdfasdfddfasdfasd");
sprintf(szDst,"%s\n%s",szHead,szDst2);

这样结果是对的！
===================
你那种结果你算算一共出现多少Head我算了一共是5个Head+ 1个H
刚刚好是你的"adfasdfasdfddfasdfasd"长度！
===================
如果你这样"adfasdfasdfddfasdfasd111"
如同你的做法出现6个完整Head
===================
如果你这样
char szHead[10];
char szDst[256];

strcpy(szHead,"Head");
strcpy(szDst,"adfasdfasdfddfasdfasd");
sprintf(szDst,"%s\n%s",szDst,szHead);// szDst - szHead换位置
结果是adfasdfasdfddfasdfasd\nHead
===================
为什么
==========
因为当szHead在前，sprintf，一上来就把szDst替换成了Head/n了，后面的那个szDst自然就是Head/n，然后操作szDst 到 szDst 等于 Head/n 后面在加 Head/n 结果整个 szDst 全成了 Head/n
====================
避免办法就是用szDst2
====================
谢谢你的100分，疯狂程序员要了！

[qing_li73]

Write formatted data to a string.

int sprintf( char *buffer, const char *format [, argument] ... );

u see, the first parameter is an address of buffer .. its value has changed from "adfasdfasdfddfasdfasd" to "Head" when u want to add itself :)

[Zark]

此类问题在MSDN关于sprintf()函数的介绍中早已讲清楚了,楼主没有认真地读啊!

Remarks

The sprintf function formats and stores a series of characters and values in buffer. Each argument (if any) is converted and output according to the corresponding format specification in format. The format consists of ordinary characters and has the same form and function as the format argument for printf. A null character is appended after the last character written. If copying occurs between strings that overlap, the behavior is undefined.

最后一句,"如果在互有重叠的字符串之间进行拷贝,其后果是不可预料的".

[Truman]

那么结果应该是两个head, "HEAD\nHead"才对啊,怎么那么多呢?