C程序参考,简单易懂,是初学者不可少的参考资料

				#include
				#include
				void main()
				{  FILE *fp;char  ch;
				   if((fp=fopen("d:\\aaaa.txt","r+"))==NULL)
				   {     printf("Cann't Open File d:\\a1.txt");
				         exit(0);
				   }
				   ch=fgetc(fp);
				   while(!feof(fp))
				   { 
				        if(ch!='%')
					{   ch=ch-10;
				  fseek(fp,-1L,1);
				fputc(ch,fp);
				fseek(fp,0L,1);
				}
				      ch=fgetc(fp);
				   }
				   fclose(fp);
				}