只是简单的数据库链接，预编译成的C语言代码，有个地方不明白。

看两种定义展开成C代码后的区别：
第一种定义链接数据库的用户名和密码：#define     LEN        40
VARCHAR     username[LEN];
varchar     password[LEN];   strncpy((char *) username.arr, "SCOTT", LEN);
username.len = (unsigned short) strlen((char *) username.arr);strncpy((char *) password.arr, "TIGER", LEN);
password.len = (unsigned short) strlen((char *) password.arr);EXEC SQL CONNECT :username IDENTIFIED BY :password; // 这句预编译后的C代码：{
...
    sqlstm.sqhstv[0] = (unsigned char  *)&username;
    sqlstm.sqhstl[0] = (unsigned long )42;
    sqlstm.sqhsts[0] = (         int  )42;
...    sqlstm.sqhstv[1] = (unsigned char  *)&password;
    sqlstm.sqhstl[1] = (unsigned long )42;
    sqlstm.sqhsts[1] = (         int  )42;
...
}第二种定义链接数据库的用户名和密码：#define     LEN        40typedef char asciiz[LEN];
asciiz     username;
asciiz     password; strcpy(username, "SCOTT");
strcpy(password, "TIGER"); EXEC SQL CONNECT :username IDENTIFIED BY :password; // 这句预编译后的C代码：
{
...
    sqlstm.sqhstv[0] = (unsigned char  *)username;
    sqlstm.sqhstl[0] = (unsigned long )40;
    sqlstm.sqhsts[0] = (         int  )40;
...
    sqlstm.sqhstv[1] = (unsigned char  *)password;
    sqlstm.sqhstl[1] = (unsigned long )40;
    sqlstm.sqhsts[1] = (         int  )40;
...
}

第一种 VARCHAR 类型的定义是怎么样的？C里面没这个类型的

两种定义的.pc文件代码：#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sqlda.h>
#include <sqlcpr.h>
#define     LEN        40VARCHAR     username[LEN];
varchar     password[LEN];   void sql_error(msg)
    char *msg;
{
    char err_msg[512];
    size_t buf_len, msg_len;    EXEC SQL WHENEVER SQLERROR CONTINUE;    printf("\n%s\n", msg);/* Call sqlglm() to get the complete text of the
* error message.
*/
    buf_len = sizeof (err_msg);
    sqlglm(err_msg, &buf_len, &msg_len);
    printf("%.*s\n", msg_len, err_msg);    EXEC SQL ROLLBACK RELEASE;
    exit(EXIT_FAILURE);
} void main()
{
    strncpy((char *) username.arr, "SCOTT", LEN);
    username.len =
      (unsigned short) strlen((char *) username.arr);    strncpy((char *) password.arr, "TIGER", LEN);
    password.len =
      (unsigned short) strlen((char *) password.arr);   EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--");/* Connect to ORACLE. */
    EXEC SQL CONNECT :username IDENTIFIED BY :password;    printf("\nConnected to ORACLE as user: %s\n", username.arr);/* Disconnect from ORACLE. */
    EXEC SQL ROLLBACK WORK RELEASE;
    exit(EXIT_SUCCESS);
}#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sqlda.h>
#include <sqlcpr.h>
#define     LEN        40typedef char asciiz[LEN];
asciiz     username;
asciiz     password;    void sql_error(msg)
    char *msg;
{
    char err_msg[512];
    size_t buf_len, msg_len;    EXEC SQL WHENEVER SQLERROR CONTINUE;    printf("\n%s\n", msg);/* Call sqlglm() to get the complete text of the
* error message.
*/
    buf_len = sizeof (err_msg);
    sqlglm(err_msg, &buf_len, &msg_len);
    printf("%.*s\n", msg_len, err_msg);    EXEC SQL ROLLBACK RELEASE;
    exit(EXIT_FAILURE);
} void main()
{
    strcpy(username, "SCOTT");
    strcpy(password, "TIGER");     EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--");/* Connect to ORACLE. */
    EXEC SQL CONNECT :username IDENTIFIED BY :password;    printf("\nConnected to ORACLE as user: %s\n", username); /* Disconnect from ORACLE. */
    EXEC SQL ROLLBACK WORK RELEASE;
    exit(EXIT_SUCCESS);
}

还是没看到VARCHAR类型是如何定义的

回复 5 楼 edcvf3额，你不会是不会用proc预编译吧

没用过PROC ，用过C，知道头文件里应该有类型定义,可惜你不给看啊

好吧，我把两个预编译后的.c文件代码贴出来：/* Result Sets Interface */
#ifndef SQL_CRSR
#  define SQL_CRSR
  struct sql_cursor
  {
    unsigned int curocn;
    void *ptr1;
    void *ptr2;
    unsigned int magic;
  };
  typedef struct sql_cursor sql_cursor;
  typedef struct sql_cursor SQL_CURSOR;
#endif /* SQL_CRSR *//* Thread Safety */
typedef void * sql_context;
typedef void * SQL_CONTEXT;/* Object support */
struct sqltvn
{
  unsigned char *tvnvsn;
  unsigned short tvnvsnl;
  unsigned char *tvnnm;
  unsigned short tvnnml;
  unsigned char *tvnsnm;
  unsigned short tvnsnml;
};
typedef struct sqltvn sqltvn;struct sqladts
{
  unsigned int adtvsn;
  unsigned short adtmode;
  unsigned short adtnum;
  sqltvn adttvn[1];
};
typedef struct sqladts sqladts;static struct sqladts sqladt = {
  1,1,0,
};/* Binding to PL/SQL Records */
struct sqltdss
{
  unsigned int tdsvsn;
  unsigned short tdsnum;
  unsigned char *tdsval[1];
};
typedef struct sqltdss sqltdss;
static struct sqltdss sqltds =
{
  1,
  0,
};/* File name & Package Name */
struct sqlcxp
{
  unsigned short fillen;
           char  filnam[9];
};
static struct sqlcxp sqlfpn =
{
    8,
    "test1.pc"
};
static unsigned int sqlctx = 19971;
static struct sqlexd {
   unsigned long  sqlvsn;
   unsigned int   arrsiz;
   unsigned int   iters;
   unsigned int   offset;
   unsigned short selerr;
   unsigned short sqlety;
   unsigned int   occurs;
            short *cud;
   unsigned char  *sqlest;
            char  *stmt;
   sqladts *sqladtp;
   sqltdss *sqltdsp;
   unsigned char  **sqphsv;
   unsigned long  *sqphsl;
            int   *sqphss;
            short **sqpind;
            int   *sqpins;
   unsigned long  *sqparm;
   unsigned long  **sqparc;
   unsigned short  *sqpadto;
   unsigned short  *sqptdso;
   unsigned int   sqlcmax;
   unsigned int   sqlcmin;
   unsigned int   sqlcincr;
   unsigned int   sqlctimeout;
   unsigned int   sqlcnowait;
            int   sqfoff;
   unsigned int   sqcmod;
   unsigned int   sqfmod;
   unsigned char  *sqhstv[4];
   unsigned long  sqhstl[4];
            int   sqhsts[4];
            short *sqindv[4];
            int   sqinds[4];
   unsigned long  sqharm[4];
   unsigned long  *sqharc[4];
   unsigned short  sqadto[4];
   unsigned short  sqtdso[4];
} sqlstm = {12,4};/* SQLLIB Prototypes */
extern sqlcxt ( void **, unsigned int *,
                   struct sqlexd *, struct sqlcxp * );
extern sqlcx2t( void **, unsigned int *,
                   struct sqlexd *, struct sqlcxp * );
extern sqlbuft( void **, char * );
extern sqlgs2t( void **, char * );
extern sqlorat( void **, unsigned int *, void * );/* Forms Interface */
static int IAPSUCC = 0;
static int IAPFAIL = 1403;
static int IAPFTL  = 535;
extern void sqliem( unsigned char *, signed int * );typedef struct { unsigned short len; unsigned char arr[1]; } VARCHAR;
typedef struct { unsigned short len; unsigned char arr[1]; } varchar;/* CUD (Compilation Unit Data) Array */
static short sqlcud0[] =
{12,4130,1,0,0,
5,0,0,1,0,0,32,31,0,0,0,0,0,1,0,
20,0,0,0,0,0,27,48,0,0,4,4,0,1,0,1,9,0,0,1,9,0,0,1,10,0,0,1,10,0,0,
51,0,0,3,0,0,32,53,0,0,0,0,0,1,0,
};#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sqlda.h>
#include <sqlcpr.h>
#define     LEN        40/* VARCHAR     username[LEN]; */
struct { unsigned short len; unsigned char arr[40]; } username;

/* varchar     password[LEN]; */
struct { unsigned short len; unsigned char arr[40]; } password;
   void sql_error(msg)
    char *msg;
{
    char err_msg[512];
    size_t buf_len, msg_len;    /* EXEC SQL WHENEVER SQLERROR CONTINUE; */
    printf("\n%s\n", msg);/* Call sqlglm() to get the complete text of the
* error message.
*/
    buf_len = sizeof (err_msg);
    sqlglm(err_msg, &buf_len, &msg_len);
    printf("%.*s\n", msg_len, err_msg);    /* EXEC SQL ROLLBACK RELEASE; */ {
    struct sqlexd sqlstm;
    sqlstm.sqlvsn = 12;
    sqlstm.arrsiz = 0;
    sqlstm.sqladtp = &sqladt;
    sqlstm.sqltdsp = &sqltds;
    sqlstm.iters = (unsigned int  )1;
    sqlstm.offset = (unsigned int  )5;
    sqlstm.cud = sqlcud0;
    sqlstm.sqlest = (unsigned char  *)&sqlca;
    sqlstm.sqlety = (unsigned short)4352;
    sqlstm.occurs = (unsigned int  )0;
    sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
}
    exit(EXIT_FAILURE);
} void main()
{
    strncpy((char *) username.arr, "SCOTT", LEN);
    username.len =
      (unsigned short) strlen((char *) username.arr);    strncpy((char *) password.arr, "TIGER", LEN);
    password.len =
      (unsigned short) strlen((char *) password.arr);   /* EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--"); */
/* Connect to ORACLE. */
    /* EXEC SQL CONNECT :username IDENTIFIED BY :password; */ {
    struct sqlexd sqlstm;
    sqlstm.sqlvsn = 12;
    sqlstm.arrsiz = 4;
    sqlstm.sqladtp = &sqladt;
    sqlstm.sqltdsp = &sqltds;
    sqlstm.iters = (unsigned int  )10;
    sqlstm.offset = (unsigned int  )20;
    sqlstm.cud = sqlcud0;
    sqlstm.sqlest = (unsigned char  *)&sqlca;
    sqlstm.sqlety = (unsigned short)4352;
    sqlstm.occurs = (unsigned int  )0;
    sqlstm.sqhstv[0] = (unsigned char  *)&username;
    sqlstm.sqhstl[0] = (unsigned long )42;
    sqlstm.sqhsts[0] = (         int  )42;
    sqlstm.sqindv[0] = (         short *)0;
    sqlstm.sqinds[0] = (         int  )0;
    sqlstm.sqharm[0] = (unsigned long )0;
    sqlstm.sqadto[0] = (unsigned short )0;
    sqlstm.sqtdso[0] = (unsigned short )0;
    sqlstm.sqhstv[1] = (unsigned char  *)&password;
    sqlstm.sqhstl[1] = (unsigned long )42;
    sqlstm.sqhsts[1] = (         int  )42;
    sqlstm.sqindv[1] = (         short *)0;
    sqlstm.sqinds[1] = (         int  )0;
    sqlstm.sqharm[1] = (unsigned long )0;
    sqlstm.sqadto[1] = (unsigned short )0;
    sqlstm.sqtdso[1] = (unsigned short )0;
    sqlstm.sqphsv = sqlstm.sqhstv;
    sqlstm.sqphsl = sqlstm.sqhstl;
    sqlstm.sqphss = sqlstm.sqhsts;
    sqlstm.sqpind = sqlstm.sqindv;
    sqlstm.sqpins = sqlstm.sqinds;
    sqlstm.sqparm = sqlstm.sqharm;
    sqlstm.sqparc = sqlstm.sqharc;
    sqlstm.sqpadto = sqlstm.sqadto;
    sqlstm.sqptdso = sqlstm.sqtdso;
    sqlstm.sqlcmax = (unsigned int )100;
    sqlstm.sqlcmin = (unsigned int )2;
    sqlstm.sqlcincr = (unsigned int )1;
    sqlstm.sqlctimeout = (unsigned int )0;
    sqlstm.sqlcnowait = (unsigned int )0;
    sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
    if (sqlca.sqlcode < 0) sql_error("ORACLE error--");
}    printf("\nConnected to ORACLE as user: %s\n", username.arr);/* Disconnect from ORACLE. */
    /* EXEC SQL ROLLBACK WORK RELEASE; */ {
    struct sqlexd sqlstm;
    sqlstm.sqlvsn = 12;
    sqlstm.arrsiz = 4;
    sqlstm.sqladtp = &sqladt;
    sqlstm.sqltdsp = &sqltds;
    sqlstm.iters = (unsigned int  )1;
    sqlstm.offset = (unsigned int  )51;
    sqlstm.cud = sqlcud0;
    sqlstm.sqlest = (unsigned char  *)&sqlca;
    sqlstm.sqlety = (unsigned short)4352;
    sqlstm.occurs = (unsigned int  )0;
    sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
    if (sqlca.sqlcode < 0) sql_error("ORACLE error--");
}
    exit(EXIT_SUCCESS);
}

/* Result Sets Interface */
#ifndef SQL_CRSR
#  define SQL_CRSR
  struct sql_cursor
  {
    unsigned int curocn;
    void *ptr1;
    void *ptr2;
    unsigned int magic;
  };
  typedef struct sql_cursor sql_cursor;
  typedef struct sql_cursor SQL_CURSOR;
#endif /* SQL_CRSR *//* Thread Safety */
typedef void * sql_context;
typedef void * SQL_CONTEXT;/* Object support */
struct sqltvn
{
  unsigned char *tvnvsn;
  unsigned short tvnvsnl;
  unsigned char *tvnnm;
  unsigned short tvnnml;
  unsigned char *tvnsnm;
  unsigned short tvnsnml;
};
typedef struct sqltvn sqltvn;struct sqladts
{
  unsigned int adtvsn;
  unsigned short adtmode;
  unsigned short adtnum;
  sqltvn adttvn[1];
};
typedef struct sqladts sqladts;static struct sqladts sqladt = {
  1,1,0,
};/* Binding to PL/SQL Records */
struct sqltdss
{
  unsigned int tdsvsn;
  unsigned short tdsnum;
  unsigned char *tdsval[1];
};
typedef struct sqltdss sqltdss;
static struct sqltdss sqltds =
{
  1,
  0,
};/* File name & Package Name */
struct sqlcxp
{
  unsigned short fillen;
           char  filnam[9];
};
static struct sqlcxp sqlfpn =
{
    8,
    "test2.pc"
};
static unsigned int sqlctx = 19979;
static struct sqlexd {
   unsigned long  sqlvsn;
   unsigned int   arrsiz;
   unsigned int   iters;
   unsigned int   offset;
   unsigned short selerr;
   unsigned short sqlety;
   unsigned int   occurs;
            short *cud;
   unsigned char  *sqlest;
            char  *stmt;
   sqladts *sqladtp;
   sqltdss *sqltdsp;
   unsigned char  **sqphsv;
   unsigned long  *sqphsl;
            int   *sqphss;
            short **sqpind;
            int   *sqpins;
   unsigned long  *sqparm;
   unsigned long  **sqparc;
   unsigned short  *sqpadto;
   unsigned short  *sqptdso;
   unsigned int   sqlcmax;
   unsigned int   sqlcmin;
   unsigned int   sqlcincr;
   unsigned int   sqlctimeout;
   unsigned int   sqlcnowait;
            int   sqfoff;
   unsigned int   sqcmod;
   unsigned int   sqfmod;
   unsigned char  *sqhstv[4];
   unsigned long  sqhstl[4];
            int   sqhsts[4];
            short *sqindv[4];
            int   sqinds[4];
   unsigned long  sqharm[4];
   unsigned long  *sqharc[4];
   unsigned short  sqadto[4];
   unsigned short  sqtdso[4];
} sqlstm = {12,4};/* SQLLIB Prototypes */
extern sqlcxt ( void **, unsigned int *,
                   struct sqlexd *, struct sqlcxp * );
extern sqlcx2t( void **, unsigned int *,
                   struct sqlexd *, struct sqlcxp * );
extern sqlbuft( void **, char * );
extern sqlgs2t( void **, char * );
extern sqlorat( void **, unsigned int *, void * );/* Forms Interface */
static int IAPSUCC = 0;
static int IAPFAIL = 1403;
static int IAPFTL  = 535;
extern void sqliem( unsigned char *, signed int * );typedef struct { unsigned short len; unsigned char arr[1]; } VARCHAR;
typedef struct { unsigned short len; unsigned char arr[1]; } varchar;/* CUD (Compilation Unit Data) Array */
static short sqlcud0[] =
{12,4130,1,0,0,
5,0,0,1,0,0,32,32,0,0,0,0,0,1,0,
20,0,0,0,0,0,27,44,0,0,4,4,0,1,0,1,97,0,0,1,97,0,0,1,10,0,0,1,10,0,0,
51,0,0,3,0,0,32,49,0,0,0,0,0,1,0,
};#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sqlda.h>
#include <sqlcpr.h>
#define     LEN        40typedef char asciiz[LEN];
asciiz     username;
asciiz     password;    void sql_error(msg)
    char *msg;
{
    char err_msg[512];
    size_t buf_len, msg_len;    /* EXEC SQL WHENEVER SQLERROR CONTINUE; */
    printf("\n%s\n", msg);/* Call sqlglm() to get the complete text of the
* error message.
*/
    buf_len = sizeof (err_msg);
    sqlglm(err_msg, &buf_len, &msg_len);
    printf("%.*s\n", msg_len, err_msg);    /* EXEC SQL ROLLBACK RELEASE; */ {
    struct sqlexd sqlstm;
    sqlstm.sqlvsn = 12;
    sqlstm.arrsiz = 0;
    sqlstm.sqladtp = &sqladt;
    sqlstm.sqltdsp = &sqltds;
    sqlstm.iters = (unsigned int  )1;
    sqlstm.offset = (unsigned int  )5;
    sqlstm.cud = sqlcud0;
    sqlstm.sqlest = (unsigned char  *)&sqlca;
    sqlstm.sqlety = (unsigned short)4352;
    sqlstm.occurs = (unsigned int  )0;
    sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
}
    exit(EXIT_FAILURE);
} void main()
{
    strcpy(username, "SCOTT");
    strcpy(password, "TIGER");     /* EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--"); */
/* Connect to ORACLE. */
    /* EXEC SQL CONNECT :username IDENTIFIED BY :password; */ {
    struct sqlexd sqlstm;
    sqlstm.sqlvsn = 12;
    sqlstm.arrsiz = 4;
    sqlstm.sqladtp = &sqladt;
    sqlstm.sqltdsp = &sqltds;
    sqlstm.iters = (unsigned int  )10;
    sqlstm.offset = (unsigned int  )20;
    sqlstm.cud = sqlcud0;
    sqlstm.sqlest = (unsigned char  *)&sqlca;
    sqlstm.sqlety = (unsigned short)4352;
    sqlstm.occurs = (unsigned int  )0;
    sqlstm.sqhstv[0] = (unsigned char  *)username;
    sqlstm.sqhstl[0] = (unsigned long )40;
    sqlstm.sqhsts[0] = (         int  )40;
    sqlstm.sqindv[0] = (         short *)0;
    sqlstm.sqinds[0] = (         int  )0;
    sqlstm.sqharm[0] = (unsigned long )0;
    sqlstm.sqadto[0] = (unsigned short )0;
    sqlstm.sqtdso[0] = (unsigned short )0;
    sqlstm.sqhstv[1] = (unsigned char  *)password;
    sqlstm.sqhstl[1] = (unsigned long )40;
    sqlstm.sqhsts[1] = (         int  )40;
    sqlstm.sqindv[1] = (         short *)0;
    sqlstm.sqinds[1] = (         int  )0;
    sqlstm.sqharm[1] = (unsigned long )0;
    sqlstm.sqadto[1] = (unsigned short )0;
    sqlstm.sqtdso[1] = (unsigned short )0;
    sqlstm.sqphsv = sqlstm.sqhstv;
    sqlstm.sqphsl = sqlstm.sqhstl;
    sqlstm.sqphss = sqlstm.sqhsts;
    sqlstm.sqpind = sqlstm.sqindv;
    sqlstm.sqpins = sqlstm.sqinds;
    sqlstm.sqparm = sqlstm.sqharm;
    sqlstm.sqparc = sqlstm.sqharc;
    sqlstm.sqpadto = sqlstm.sqadto;
    sqlstm.sqptdso = sqlstm.sqtdso;
    sqlstm.sqlcmax = (unsigned int )100;
    sqlstm.sqlcmin = (unsigned int )2;
    sqlstm.sqlcincr = (unsigned int )1;
    sqlstm.sqlctimeout = (unsigned int )0;
    sqlstm.sqlcnowait = (unsigned int )0;
    sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
    if (sqlca.sqlcode < 0) sql_error("ORACLE error--");
}    printf("\nConnected to ORACLE as user: %s\n", username); /* Disconnect from ORACLE. */
    /* EXEC SQL ROLLBACK WORK RELEASE; */ {
    struct sqlexd sqlstm;
    sqlstm.sqlvsn = 12;
    sqlstm.arrsiz = 4;
    sqlstm.sqladtp = &sqladt;
    sqlstm.sqltdsp = &sqltds;
    sqlstm.iters = (unsigned int  )1;
    sqlstm.offset = (unsigned int  )51;
    sqlstm.cud = sqlcud0;
    sqlstm.sqlest = (unsigned char  *)&sqlca;
    sqlstm.sqlety = (unsigned short)4352;
    sqlstm.occurs = (unsigned int  )0;
    sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
    if (sqlca.sqlcode < 0) sql_error("ORACLE error--");
}
    exit(EXIT_SUCCESS);
}

struct { unsigned short len; unsigned char arr[40]; }
然后VARCHAR类型定义是结构体,那么&username就是取该结构体首地址了.你第二种,USERNAME被定义的类型是字符数组,username可以直接当数组首地址使用

&username取该结构体首地址，也就是username.len地址，不是username.arr地址。有这么大差别，为什么两个程序功能相同？

调试易

只是简单的数据库链接，预编译成的C语言代码，有个地方不明白。

解决方案 »