对磁盘文件的简单读写操作

#include <stdio.h>
#include<string.h>
int main()
 {
   int i,ch;
   char str[100];
   FILE *fp;
   fp=fopen("myfile","w");     //创建一个文件
   while(1)
     {
	  printf("input string:\n");
      gets(str);
      fprintf(fp,"%s",str);
      printf("continue?");
      ch=getchar();
      if ((ch=='N')||(ch=='n'))
    	break;
      getchar();
     }

   fclose(fp);
   fp=fopen("myfile","r");    //开始读取文件
   while(fscanf(fp,"%s",str)!=EOF)
   {
     for (i=0;str[i]!='\0';i++)
	 {
	    if ((str[i]>='A') && (str[i]<='Z')) //大小写转换
	       str[i]+=32;
	 }
      printf("%s\n",str);   

   }
   fclose(fp);
   return 0;