MYSQL c API相关问题

  
  1 #include<stdio.h>
  2 #include<stdlib.h>
  3 #include<mysql.h>
  4 #include<string.h>
  5  24 int main(){
 25         char* DBName = "judge";
 26         MYSQL *conn_ptr; 28         conn_ptr = mysql_init(NULL);
 29         conn_ptr =   mysql_real_connect(conn_ptr,"localhost","root","hjhlovehf",DBName,0,NULL,0);
 30 
 31         MYSQL_RES* res_answer;//保存从answer表中得到的数据
 32         MYSQL_RES* res_user_answer;//保存从user_answer_order_prim表中得到的数据
 33 
 34         int res;
 35 
 36         char *selectUA = "select id,user_id,user_name,answer,status from user_answer_order_prim";
 37         char *selectA = "select answer from answer1";
 38         char insertUAP[128];//往user_answer_precision表中插入结果  如果声明为指针将出错
 39 
 40         res = mysql_query(conn_ptr,selectUA);
 41         if(res){
 42                 fprintf(stderr,"select from user_answer_order_prim error:%s\n",mysql_error(conn_ptr));
 43                 exit(EXIT_FAILURE);
 44         }
 45         else{
46                 res_user_answer = mysql_store_result(conn_ptr);
 47                 printf("select %lu rows from user_answer_order_prim\n",(unsigned long)mysql_num_rows(res_user_answer));
 48         }
 49 
 50         MYSQL_ROW row_answer;
 51         MYSQL_ROW row_user_answer;
 52 
 53         int flag = 1;
 54         row_user_answer = mysql_fetch_row(res_user_answer);
 55         int count = 0;//代表人数
 56         int hundred = 0;//每个人100条记录
 57         int ten = 0;//每个人的100天记录分成10份
 58         char* user_name;
 59         char* user_id;
 60         double precision[10];
 61 
 62         while(count<76){
 63 
 64                 res = mysql_query(conn_ptr,selectA);
 65                 if(res){
 66                         fprintf(stderr,"select from answer error:%s\n",mysql_error(conn_ptr));
 67                         exit(EXIT_FAILURE);
 68                 }
 69                 else{
 70                         res_answer=mysql_store_result(conn_ptr);
 71                         printf("select %lu rows from answer\n",(unsigned long)mysql_num_rows(res_answer));
 72                 }
 73                 while(flag && hundred<100){
 74 
 75                         if(hundred == 0){
 76                                 user_id = row_user_answer[1]; 78                                 user_name = row_user_answer[2];
 79                         }
 80                         double right = 0;
 81                         while(ten<10){
 82                                 if(!(row_answer=mysql_fetch_row(res_answer))){ 84                                         break;
 85                                 }
 89                                 if(!strcmp(row_user_answer[3],row_answer[0])){
 90                                         right++;
 91                                 }
 92                                 if(!(row_user_answer = mysql_fetch_row(res_user_answer))){
 93                                         flag = 0;
 94                                         break;
 95                                 }
 96                                 ten++;
 97                                 hundred++;
 98                         }
 99                         precision[(hundred-1)/10] = right/10;
100                         ten =0;
101                 }103                 count++;
104                 hundred=0;
105                 sprintf(insertUAP,"insert into user_answer_precision(user_id,user_name,one,two,three,four,five,six,seven,eight,nine,ten) values('%s','%s',%f,%f,%f,%f,%f,%f,%f,%f,%f,%f)",user_id    ,user_name,precision[0],precision[1],precision[2],precision[3],precision[4],precision[5],precision[6],precision[7],precision[8],precision[9]);
106 printf("%s\n",insertUAP);
107                 //mysql_data_seek(res_answer,0);//重置answer表结果集到第一行    
108                 mysql_free_result(res_answer);//编译通过，运行是提示Segmentation fault
109                 res = mysql_query(conn_ptr,insertUAP);
110                 if(res){
111                         fprintf(stderr,"insert into user_answer_precision error:%s\n",mysql_error(conn_ptr));
112                 }
113                 int i;
114                 for(i = 0;i<10;i++){
115                         precision[i]=0;
116                 }
117         }
118 
119 
120         mysql_free_result(res_user_answer);
121         mysql_close(conn_ptr);123         exit(EXIT_SUCCESS);
124 
                                                                                         以上程序编译通过，运行时出现Segmentation fault错误，一直没找到原因，本人对mysql c api不是很熟悉
调试时108行提示一下错误：
Program received signal SIGSEGV, Segmentation fault.
0x00641b81 in mysql_free_result () from /usr/lib/mysql/libmysqlclient.so.15有人碰到过这种情况吗？有的话麻烦告知，还有就是运用mysql c api的时候有什么需要特别注意的？最后想问一下关于mysql中统一中文编码问题，能不能给个详细的设置步骤。谢谢！