字符串如此连接为何不可?
#include <iostream.h>
#include <string.h>
void main()
{ char *s1="first";
char s2[20]="second";
char s3[10]="third";
char s4[30];
strcpy(s4,s1);
strcat(s4,s2);
strcat(s4,s3);
cout<<"s4:"<<s4<<endl;
cout<<strcat(s1,strncat(s2,s3,3))<<endl;//运行到该语句时出现错误,错在哪里?
}