标准文件读写操作

1、编程实现读出磁盘文件datafile.txt中的内容，将它们显示在屏幕上

#include < stdio.h >
#include < stdlib.h >
#include < conio.h >

void  main()
{
    FILE  * fp;
     char  ch;
     if ((fp = fopen( " c:\\datafile.txt " , " r " )) == NULL)
    {
        printf( " file cannot be opened!\n " );
        exit( 1 );
    }
     while ((ch = fgetc(fp)) != EOF)
        fputc(ch,stdout);
    fclose(fp);
    getch();
}

2、编程完成从键盘输入字符后，写入到磁盘文件datafile.txt中

#include < stdio.h >
#include < stdlib.h >
#include < conio.h >

void  main()
{
    FILE  * fp;
     char  ch;
     if ((fp = fopen( " c:\\datafile.txt " , " w " )) == NULL)
    {
        printf( " file cannot be opened!\n " );
        exit( 1 );
    }
     while ((ch = fgetc(stdin)) != ' \n ' )
        fputc(ch,fp);
    fclose(fp);
    getch();
}

3、逐行读出datafile.txt文件中的字符并显示出来

#include < stdio.h >
#include < stdlib.h >
#include < conio.h >

void  main()
{
    FILE  * fp;
     char  buffer[ 64 ];
     if ((fp = fopen( " c:\\datafile.txt " , " r " )) == NULL)
    {
        printf( " file cannot be opened!\n " );
        exit( 1 );
    }
     while ( ! feof(fp))
    {
         if (fgets(buffer, 64 ,fp) != NULL)
            printf( " %s " ,buffer);
    }
    fclose(fp);
    getch();
}

4、从键盘输入若干行字符，把它们添加到磁盘文件datafile.txt中

#include < stdio.h >
#include < stdlib.h >
#include < conio.h >
#include < string .h >

void  main()
{
    FILE  * fp;
     char  buffer[ 64 ];
     if ((fp = fopen( " c:\\datafile.txt " , " a " )) == NULL)
    {
        printf( " file cannot be opened!\n " );
        exit( 1 );
    }
     while (strlen(fgets(buffer, 64 ,stdin)) > 1 )
    {
        fputs(buffer,fp);
        fputs( " \n " ,fp);
    }
    fclose(fp);
    getch();
}