檔案操作之fread()和fwrite()函數

標籤：c語言   檔案操作   

size_t  fwrite( const void *buffer, size_t size, size_t count, FILE *stream );buffer-指向要寫資料的儲存位置size-目標所佔位元組數count-寫目標的最大數量，即寫入多少個size大小的資料stream-檔案結構指標

舉例：

定義一個結構體

struct student{int      nID; //學號char     chName[20];    //姓名float    fScores[2];    //2門課的成績};

 void main() { int i=0; FILE *fp; struct student tStu[3]={{1,"jx",99,100},                         {2, "slkd",89, 90},                         {3, "sldd", 100, 78}};//結構體數組 if((fp = fopen("F:\\1.txt", "wb")) == 0)  {  printf("func fopen() err!\n");  return;  }  for(i=0; i<3; i++)  {  if(fwrite(&tStu[i],sizeof(struct student),1,fp)!=1)  {  printf("func fwrite() err !\n");  return;  }  }    fclose(fp);  }

以上代碼在F盤寫入位元據

下面用fread()函數讀出：

size_t  fread( void *buffer, size_t size, size_t count, FILE *stream );buffer-指向資料的儲存位置size-目標所佔位元組數count-讀取目標的最大數量，即讀取多少個size大小的資料stream-檔案結構指標

void main(){FILE *pRead;struct student tStu[4];//結構體數組struct student *ptStu = NULL;int nCount = 0;//開啟檔案 用於讀取pRead=fopen("F:/1.txt","rb");if(NULL == pRead){printf("func fopen() err ! \n");return;}//一條條的讀取ptStu = tStu;nCount = fread(ptStu,sizeof(struct student),1,pRead);while(nCount>0){printf("%d %s %.1f %.1f\n",ptStu->nID,ptStu->chName,ptStu->fScores[0],ptStu->fScores[1]);ptStu++;nCount = fread(ptStu,sizeof(struct student),1,pRead);}fclose(pRead);}

結果如下：

檔案操作之fread()和fwrite()函數