注意!不要忘记加上字符串结束符'\0'

#include <iostream>
using namespace std;
# define N 1000
void MyStrcat(char dstStr[],char srcStr[]){
    char *p = dstStr;
    char *q = srcStr;
    while (*p != '\0'){
        p++;
    }
    while (*q != '\0'){
        *p++ = *q++;
    }
    *p = '\0';	//不要忘记加上字符串结束符'\0'
}
int main() {
    char str1[N],str2[N];
    while (cin >> str1 >> str2) { // 注意 while 处理多个 case
        MyStrcat(str1, str2);
        cout << str1 << endl;
        //cout << str2 << endl;
    }
}
// 64 位输出请用 printf("%lld")