9-22.txt

C++完美演绎源代码

/* 范例：9-22 */
#include <stdio.h>

struct mystruct
{
  int i;
  char str[10];
};

int main(int argc,char *argv[])
{
  FILE *fp1;
  struct mystruct s={97,"ABCDEF"};
  float a=66.14;
  char b='C';
  int i;

  if ((fp1 = fopen(argv[1], "w")) == NULL)
  {
    fprintf(stderr, "Cannot open output file.\n");
    return 1;
  }

  fwrite(&s, sizeof(s), 1, fp1); 	/* 将结构s写入fp1 */
  fwrite(&a,sizeof(float),1,fp1); 	/* 将变量a写入fp1 */
  fwrite(&b,sizeof(char),1,fp1);  	/* 将变量b写入fp1 */

  fclose(fp1);  				/* 关闭文件 */
  fp1=fopen(argv[1],"r");
  s.i = 0;
  s.str[0]='\0';
  i=fread(&s,sizeof(s),1,fp1); 		/* 读取变量s */
  printf("i=%d s.i=%d s.str=%s\n",i,s.i,s.str);

  fread(&a,sizeof(a),1,fp1); 		/* 读取变量a */
  printf("%5.2f\n",a);

  fread(&b,sizeof(b),1,fp1);		/* 读取变量b */
  printf("%c\n",b);

  return 0;
}

程序执行结果：
D:\TC>p9-22 out.txt
i=1 s.i=97 s.str=ABCDEF
66.14
C