文档首页/ 云数据库 GaussDB/ 开发指南（分布式_V2.0-10.x）/ 应用程序开发教程/ 基于ecpg开发/ 典型应用开发示例/ 解析、运算数值类型
更新时间：2026-07-28 GMT+08:00
查看PDF
分享

解析、运算数值类型

此示例使用pgtypes库函数对numeric类型进行不同操作。 
#include <stdio.h>
#include <stdlib.h>
#include <pgtypes_numeric.h>
#include <pgtypes_error.h>
#include <decimal.h>

char* nums[] = { "2E394", "-2", ".794", "3.44", "592.49E21", "-32.84e4",
                 "2E-394", ".1E-2", "+.0", "-592.49E-07", "+32.84e-4",
                 ".500001", "-.5000001",
                 "1234567890123456789012345678.91", /* 30个数位应转换为十进制 */
                 "1234567890123456789012345678.921", /* 31个数位的数字不应转为十进制 */
                 "not a number",
                 NULL
                };

static void check_errno(void);

int main(void)
{
    char *text="error\n";
    char *endptr;
    numeric *num, *nin;
    decimal *dec;
    long l;
    int i, j, k, q, r, count = 0;
    double d;
    numeric **numarr = (numeric **) calloc(1, sizeof(numeric));


    for (i = 0; nums[i]; i++)
    {
         /* 返回由malloc分配的字符串的指针，它包含numeric类型nums[i]的字符串表达 */
         num = PGTYPESnumeric_from_asc(nums[i], &endptr);
         if (!num) check_errno();
         if (endptr != NULL)
         {
              printf("endptr of %d is not NULL\n", i);
              if (*endptr != '\0')
                  printf("*endptr of %d is not \\0\n", i);
         }
         if (!num) continue;

         numarr = (numeric **)realloc(numarr, sizeof(numeric *) * (count + 1));
         numarr[count++] = num;

         /* 返回由malloc分配的字符串的指针，它包含numeric类型num的字符串表达 */
         text = PGTYPESnumeric_to_asc(num, -1);
         if (!text) check_errno();
         printf("num[%d,1]: %s\n", i, text); free(text);
         text = PGTYPESnumeric_to_asc(num, 0);
         if (!text) check_errno();
          printf("num[%d,2]: %s\n", i, text); free(text);
         text = PGTYPESnumeric_to_asc(num, 1);
         if (!text) check_errno();
          printf("num[%d,3]: %s\n", i, text); free(text);
         text = PGTYPESnumeric_to_asc(num, 2);
         if (!text) check_errno();
         printf("num[%d,4]: %s\n", i, text); free(text);

         /* 请求一个指向新分配的numeric变量的指针 */
         nin = PGTYPESnumeric_new();
         text = PGTYPESnumeric_to_asc(nin, 2);
         if (!text) check_errno();
         printf("num[%d,5]: %s\n", i, text); free(text);

         /* 将一个numeric类型的变量转换为长整型 */
         r = PGTYPESnumeric_to_long(num, &l);
         if (r) check_errno();
         printf("num[%d,6]: %ld (r: %d)\n", i, r?0L:l, r);
         if (r == 0)
         {
             /* 把一个长整型变量转换为一个numeric变量 */
             r = PGTYPESnumeric_from_long(l, nin);
             if (r) check_errno();
             /* 返回由malloc分配的字符串的指针，它包含numeric类型nin的字符串表达 */
             text = PGTYPESnumeric_to_asc(nin, 2);
             /* 比较两个numeric变量 */
             q = PGTYPESnumeric_cmp(num, nin);
             printf("num[%d,7]: %s (r: %d - cmp: %d)\n", i, text, r, q);
             free(text);
          }

          /* 将一个numeric类型的变量转换成整数 */
          r = PGTYPESnumeric_to_int(num, &k);
          if (r) check_errno();
          printf("num[%d,8]: %d (r: %d)\n", i, r?0:k, r);
          if (r == 0)
          {
              /* 把一个整数变量转换成一个numeric变量 */
              r = PGTYPESnumeric_from_int(k, nin);
              if (r) check_errno();
              /* 返回由malloc分配的字符串的指针，它包含numeric类型nin的字符串表达 */
              text = PGTYPESnumeric_to_asc(nin, 2);
              q = PGTYPESnumeric_cmp(num, nin);
              printf("num[%d,9]: %s (r: %d - cmp: %d)\n", i, text, r, q);
              free(text);
          }

          if (i != 6)
          {
               /* 将一个numeric类型的变量转换成双精度类型 */
               r = PGTYPESnumeric_to_double(num, &d);
               if (r) check_errno();
               printf("num[%d,10]: %g (r: %d)\n", i, r?0.0:d, r);
           }

          /* 请求一个指向新分配的numeric变量的指针 */
          dec = PGTYPESdecimal_new();
          /* 将一个decimal类型的变量转换成numeric */
          r = PGTYPESnumeric_to_decimal(num, dec);
          if (r) check_errno();
          printf("num[%d,11]: - (r: %d)\n", i, r);
          if (r == 0)
          {
              /* 将一个decimal类型的变量转换成numeric */
              r = PGTYPESnumeric_from_decimal(dec, nin);
              if (r) check_errno();
              /* 返回由malloc分配的字符串的指针，它包含numeric类型nin的字符串表达 */
              text = PGTYPESnumeric_to_asc(nin, 2);
              /* 比较两个numeric变量 */
              q = PGTYPESnumeric_cmp(num, nin);
              printf("num[%d,12]: %s (r: %d - cmp: %d)\n", i, text, r, q);
              free(text);
          }

          /* 释放numeric变量的内存 */
          PGTYPESdecimal_free(dec);
          PGTYPESnumeric_free(nin);
          printf("\n");
    }

    for (i = 0; i < count; i++)
    {
        for (j = 0; j < count; j++)
        {
            /* 请求一个指向新分配的numeric变量的指针 */
            numeric* a = PGTYPESnumeric_new();
            numeric* s = PGTYPESnumeric_new();
            numeric* m = PGTYPESnumeric_new();
            numeric* d = PGTYPESnumeric_new();
            /* 把两个numeric变量相加放到第三个numeric变量中 */
            r = PGTYPESnumeric_add(numarr[i], numarr[j], a);
            if (r)
            {
               check_errno();
               printf("r: %d\n", r);
             }
            else
            {
                /* 返回由malloc分配的字符串的指针，它包含numeric类型a的字符串表达 */
                text = PGTYPESnumeric_to_asc(a, 10);
                printf("num[a,%d,%d]: %s\n", i, j, text);
                free(text);
            }
            /* 把两个numeric变量相减并且把结果返回到第三个numeric变量 */
            r = PGTYPESnumeric_sub(numarr[i], numarr[j], s);
            if (r)
            {
                check_errno();
                printf("r: %d\n", r);
            }
            else
            {
                /* 返回由malloc分配的字符串的指针，它包含numeric类型s的字符串表达 */
                text = PGTYPESnumeric_to_asc(s, 10);
                printf("num[s,%d,%d]: %s\n", i, j, text);
                free(text);
            }
            /* 把两个numeric变量相乘并且把结果返回到第三个numeric变量 */
            r = PGTYPESnumeric_mul(numarr[i], numarr[j], m);
            if (r)
            {
                check_errno();
                printf("r: %d\n", r);
            }
            else
            {
                /* 返回由malloc分配的字符串的指针，它包含numeric类型m的字符串表达 */
                text = PGTYPESnumeric_to_asc(m, 10);
                printf("num[m,%d,%d]: %s\n", i, j, text);
                free(text);
            }
            /* 把两个numeric变量相除并且把结果返回到第三个numeric变量 */
            r = PGTYPESnumeric_div(numarr[i], numarr[j], d);
            if (r)
            {
                check_errno();
                printf("r: %d\n", r);
            }
            else
            {
                /* 返回由malloc分配的字符串的指针，它包含numeric类型d的字符串表达 */
                text = PGTYPESnumeric_to_asc(d, 10);
                printf("num[d,%d,%d]: %s\n", i, j, text);
                free(text);
            }

            /* 释放一个numeric变量的内存 */
            PGTYPESnumeric_free(a);
            PGTYPESnumeric_free(s);
            PGTYPESnumeric_free(m);
            PGTYPESnumeric_free(d);
       }
   }

    for (i = 0; i < count; i++)
    {
        /* 返回由malloc分配的字符串的指针，它包含numeric类型numarr[i]的字符串表达 */
        text = PGTYPESnumeric_to_asc(numarr[i], -1);
        printf("%d: %s\n", i, text);
        free(text);
        /* 释放内存 */
        PGTYPESnumeric_free(numarr[i]);
    }
    free(numarr);

    return (0);
}

/* 错误处理 */
static void
check_errno(void)
{
    switch(errno)
    {
        case 0:
        printf("(no errno set) - ");
        break;
        case PGTYPES_NUM_OVERFLOW:
        printf("(errno == PGTYPES_NUM_OVERFLOW) - ");
        break;
        case PGTYPES_NUM_UNDERFLOW:
        printf("(errno == PGTYPES_NUM_UNDERFLOW) - ");
        break;
        case PGTYPES_NUM_BAD_NUMERIC:
        printf("(errno == PGTYPES_NUM_BAD_NUMERIC) - ");
        break;
        case PGTYPES_NUM_DIVIDE_ZERO:
        printf("(errno == PGTYPES_NUM_DIVIDE_ZERO) - ");
        break;
        default:
        printf("(unknown errno (%d))\n", errno);
        printf("(libc: (%s)) ", strerror(errno));
        break;
    }
}

运行结果（此实例运行结果过长，此处只截取部分）：

endptr of 0 is not NULL
num[0,1]: 20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
num[0,2]: 20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
num[0,3]: 20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.0
num[0,4]: 20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.00
num[0,5]: 0.00
(errno == PGTYPES_NUM_OVERFLOW) - num[0,6]: 0 (r: -1)
(errno == PGTYPES_NUM_OVERFLOW) - num[0,8]: 0 (r: -1)
(errno == PGTYPES_NUM_OVERFLOW) - num[0,10]: 0 (r: -1)
num[0,11]: - (r: 0)
num[0,12]: 20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.00 (r: 0 - cmp: 0)

endptr of 1 is not NULL
num[1,1]: -2
num[1,2]: -2
num[1,3]: -2.0
num[1,4]: -2.00
num[1,5]: 0.00
num[1,6]: -2 (r: 0)
num[1,7]: -2.00 (r: 0 - cmp: 0)
num[1,8]: -2 (r: 0)
num[1,9]: -2.00 (r: 0 - cmp: 0)
num[1,10]: -2 (r: 0)
num[1,11]: - (r: 0)
num[1,12]: -2.00 (r: 0 - cmp: 0)

endptr of 2 is not NULL
num[2,1]: 0.794
num[2,2]: 1
num[2,3]: 0.8
num[2,4]: 0.79
num[2,5]: 0.00
num[2,6]: 1 (r: 0)
num[2,7]: 1.00 (r: 0 - cmp: -1)
num[2,8]: 1 (r: 0)
num[2,9]: 1.00 (r: 0 - cmp: -1)
num[2,10]: 0.794 (r: 0)
num[2,11]: - (r: 0)
num[2,12]: 0.79 (r: 0 - cmp: 0)

endptr of 3 is not NULL
num[3,1]: 3.44
num[3,2]: 3
num[3,3]: 3.4
num[3,4]: 3.44
num[3,5]: 0.00
num[3,6]: 3 (r: 0)
num[3,7]: 3.00 (r: 0 - cmp: 1)
num[3,8]: 3 (r: 0)
num[3,9]: 3.00 (r: 0 - cmp: 1)
num[3,10]: 3.44 (r: 0)
num[3,11]: - (r: 0)
num[3,12]: 3.44 (r: 0 - cmp: 0)

endptr of 4 is not NULL
num[4,1]: 592490000000000000000000
num[4,2]: 592490000000000000000000
num[4,3]: 592490000000000000000000.0
num[4,4]: 592490000000000000000000.00
num[4,5]: 0.00
(errno == PGTYPES_NUM_OVERFLOW) - num[4,6]: 0 (r: -1)
(errno == PGTYPES_NUM_OVERFLOW) - num[4,8]: 0 (r: -1)
num[4,10]: 5.9249e+23 (r: 0)
num[4,11]: - (r: 0)
num[4,12]: 592490000000000000000000.00 (r: 0 - cmp: 0)
...（后续省略）

相关文档