1 #include <stdio.h> 2 #include <string.h> 3 #define N 5 4  5 char *mycat(char *s1, char *s2) 6 { 7     //数组型 8 /*    int i = 0; 9     while(s1[i] != ‘\0‘) {10         i++;11     } 12     int j = 0;13     while(s2[j] != ‘\0‘) {14         s1[i] = s2[j];15         i++;16         j++;17     }18     s1[i] = ‘\0‘;19     20     return s1;   */21     //指针型22     char *p = s1;            //定义字符型指针p指向s1 23     while(*s1 != ‘\0‘) {     //让s1指向‘\0‘ 24         s1++;25     } 26     while(*s2 != ‘\0‘) {     //让s2连在s1后 27         *s1 = *s2;28         s1++;29         s2++;30     }31     *s1 = ‘\0‘;              //让s1以‘\0‘结尾 32     33     return p;34     35 }36 37 int main()38 {39     char s1[N];40     char s2[N];41     fgets(s1, N, stdin);                    42     if(s1[strlen(s1) - 1] == ‘\n‘) {      // 去掉换行符43         s1[strlen(s1) - 1] = ‘\0‘;   44     }45     fflush(stdin);                        //因为上面使用了fgets，这里得清空缓冲区（具体请看gets和fgets函数的区别）46     fgets(s2, N, stdin);47     if(s2[strlen(s2) - 1] == ‘\n‘) {      // 去掉换行符48         s2[strlen(s2) - 1] = ‘\0‘;   49     }50     printf("%s", mycat(s1, s2));51 //    printf("%s\n%s", s1, s2);52     53     return 0;