/* This program uses the va_arg macro to accept a static decimal */
/* data type of the form decimal(n,p). The va_arg macro returns */
/* the current packed decimal argument. */
#include <decimal.h>
#include <stdio.h>
#include <stdarg.h>
#define N1 3
#define N2 6
int vargf(FILE *,char *,...);
int main(void)
{
int num1 = -1, num2 = -1;
char fmt_1[]="%D(3,2)%D(3,2)%D(3,2)";
char fmt_2[]="%D(3,2)%D(3,2)%D(3,2)%D(3,2)%D(3,2)%D(3,2)";
decimal(3,2) arr_1[]={ 1.11d, -2.22d, 3.33d };
decimal(3,2) arr_2[]={ -1.11d, 2.22d, -3.33d, 4.44d, -5.55d, 6.66d};
FILE *stream_1;
FILE *stream_2;
stream_1=fopen("file_1.dat", "wb+");
num1=vargf(stream_1,fmt_1,arr_1[0],
arr_1[1],
arr_1[2]);
if (num1<0)
{
printf("An error occurred when calling function vargf first time\n");
}
else
{
printf("Number of char. printed when vargf is called first time is:%d\n",
num1);
}
stream_2=fopen("file_2.dat", "wb+");
num2=vargf(stream_2,fmt_2,arr_2[0],
arr_2[1],
arr_2[2],
arr_2[3],
arr_2[4],
arr_2[5]);
if (num2<0)
{
printf("An error occurred when calling function vargf second time\n");
}
else
{
printf("Number of char. printed when vargf is called a second time is:%d\n",
num2);
}
fclose(stream_1);
fclose(stream_2);
}
int vargf(FILE *str, char *fmt,...)
{
int result;
va_list arg_ptr;
va_start(arg_ptr, fmt);
result = vfprintf(str, fmt, arg_ptr);
va_end(arg_ptr);
return result;
}
输出如下所示:
Number of char. printed when vargf is called first time is: 13
Number of char. printed when vargf is called second time is : 27
Press ENTER to end terminal session.
/* This program shows how to write packed decimal constants to a file */
/* and scan them back again. Also shows how to pass a packed decimal */
/* array to a function. */
#include <decimal.h>
#include <stdio.h>
#include <stdlib.h>
#define N 3 /* Array size */
/* for decimal declaration. */
FILE *stream; /* File pointer declaration. */
/* Declare valid packed decimal */
/* array. */
decimal(4,2) arr_1[] = {12.35d, 25.00d, -19.58d};
decimal(4,2) arr_2[N];
void write_num(decimal(4,2) a[N]); /*Declare function to */
/*write to a file. */
void read_num(decimal(4,2) b[N]); /*Declare function to */
/*read from a file. */
int main(void)
{
int reposition=0;
/* Open the file. */
if ((stream = fopen("*CURLIB/OUTFILE","w+")) == NULL)
{
printf("Can not open file");
exit(EXIT_FAILURE);
}
write_num(arr_1); /* Call function to write */
/* values of packed decimal */
/* array to outfile with fprintf*/
/* library function. */
reposition=fseek(stream, 0L, SEEK_SET);
if (reposition!=0)
{
printf("FSEEK failed to position file pointer\n");
exit(EXIT_FAILURE);
}
read_num(arr_2); /* Call function to read */
/* values of packed decimal */
/* array from file using */
/* fscanf() function. */
fclose(stream); /* Close the file. */
}
/* write_num is passed a packed decimal array. These values are */
/* written to a text file with the fprintf library function. */
/* If the function is successful a 0 is returned, otherwise a */
/* negative value is returned (indicating an error). */
void write_num(decimal(4,2) a[N])
{
int i, j;
for (i=0;i < N;i++)
{
j = fprintf(stream,"%D(4,2)\n",a[i]);
if (j < 0)
printf("Number not written to file %D(4,2)\n",a[i]);
}
}
/* read_num is passed a packed decimal array. The values are */
/* read from a text file with the fscanf library function. */
/* If the function is successful a 0 is returned, otherwise a */
/* negative value is returned (indicating an error). */
void read_num(decimal(4,2) b[N])
{
int i, j;
for (i=0;i < sizeof(b)/sizeof(b[0]);i++)
{
j = fscanf(stream,"%D(4,2)\n",&b[i]);
if (j < 0)
printf("Error when reading from file\n");
}
printf("b[0]=%D(4,2)\nb[1]=%D(4,2)\n\
b[2]=%D(4,2)\n", b[0], b[1], b[2]);
}
输出如下所示:
b[0]=12.35
b[1]=25.00
b[2]=-19.58
Press ENTER to end terminal session.
以下示例显示如何将 %D (* ， *) 说明符与 printf() 函数配合使用。 如果要打印的变量的 n 和 p 与转换说明符 %D (n ， p) 中的 n 和 p 不匹配，那么行为未定义。 在自变量列表中使用一元运算符 digitsof (expression) 和 precisionof (expression) 来替换 D (* ， *) 中的 * ，只要生成的压缩十进制表达式类型的大小未知。图 1。 ILE C 源到打印压缩十进制常量