我下面的程序有问题。我正在尝试浏览用户输入的某些单词的字符串命令。我现在的主要问题是，当我运行以下命令时，我得到一个警告，即“传递'strcat'的arg 2会使指针从整数转换而无需强制转换”。我的意图是遍历字符串“ s”的前三个字符，将它们连接到字符串“ firstthree”，然后检查字符串“ firstthree”的值。任何帮助表示赞赏。
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <readline/readline.h>
#include <readline/history.h>
/* Simple example of using gnu readline to get lines of input from a user.
Needs to be linked with -lreadline -lcurses
add_history tells the readline library to add the line to it's
internal histiry, so that using up-arrow (or ^p) will allows the user
to see/edit previous lines.
*/
int main(int argc, char **argv) {
char …