http://blog.csdn.net/silyvin/article/details/8289047 2012 参考
feof与EOF
<转>feof()和EOF用法
fp=fopen("0.exe","rb"); 注意 ‘b'
gp=fopen("1.exe","wb");
将fp的文件指针移至末尾
用fseek然后使用ftell(fp)求出文件指针的便宜,实际上就是文件的大小
rewind文件指针malloc这么大的buffer
fread 读取文件内容
fwrite想到第二个文件中
关闭两个文件
- #include <stdio.h>
- #include <stdlib.h>
- int main()
- {
- char *sFile="1.mp3";
- char *dFile="2.mp3";
- FILE *sfp,*dfp;
- if((sfp = fopen(sFile, "rb")) == 0)
- {
- printf("源文件打开失败:%s", sFile);
- return(-1);
- }
- if((dfp = fopen(dFile, "wb")) == 0)
- {
- printf("目标文件打开失败:"+*dFile);
- return(-2);
- }
-
- fseek(sfp, 0, SEEK_END);
- int len = ftell(sfp);
-
- rewind(sfp);
- void *buffer=(void*)malloc(len);
- fread(buffer, len, 1, sfp);
- fwrite(buffer, len, 1, dfp);
- fclose(sfp);
- fclose(dfp);
- return(0);
- }
另外,也可以挨个读文件的字符实现
- #include<stdio.h>
- int main()
- {
- FILE *fpr = fopen("a.ex","rb");
- FILE *fpw = fopen("b.ex","wb");
- int ch = 0;
- while( (ch = fgetc(fpr)) != -1 )
- fputc(ch, fpw);
-
- fclose(fpr);
- fclose(fpw);
- return 0;
- }
注意
1.必须用一个int变量来接收fgetc的返回值,如果用char型变量,则接收到FF再与-1(0xFFFFFFFF)比较,会出现相等的情况,vc将后者隐式转换为char型,考虑以下代码:
- #include<stdio.h>
- int main()
- {
- char a = 0xff;
- if(0xffffffff == a)
- printf("ok\n");
-
- return 0;
- }
int定义之后,读到FF填入ch后变为0x000000FF,不会出现没有读完就退出循环的情况,当然文本文件的读写无需考虑,因为文件中不会出现FF字符。
2.这段代码会有bug,就是文件读入错误时也会返回EOF
int fgetc( FILE *stream );
fgetc returns the character read as an int or returnEOF to indicate anerror or end of file.
解决方法除了追加ferror判断,还可以用以下代码
- #include<stdio.h>
- int main()
- {
- FILE *fpr = fopen("a.ex","rb");
- FILE *fpw = fopen("b.ex","wb");
- char ch = 0;
- ch = fgetc(fpr);
- while(!feof(fpr))
- {
- fputc(ch, fpw);
- ch = fgetc(fpr);
- }
- fclose(fpr);
- fclose(fpw);
- return 0;
- }
应避免
- #include<stdio.h>
- int main()
- {
- FILE *fpr = fopen("a.ex","rb");
- FILE *fpw = fopen("b.ex","wb");
- char ch = 0;
- while(!feof(fpr))
- {
- ch = fgetc(fpr);
- fputc(ch, fpw);
- }
- fclose(fpr);
- fclose(fpw);
- return 0;
- }
这套代码最终会在文件最后加上FF字符,用WinHex查看
原因就是在读完最后一个字符后,fp->flag仍然没有被置为_IOEOF,因而feof()仍然没有探测到文件结尾。直到再次调用fgetc()执行读操作,feof()才能探测到文件结尾。这样就多输出了一个-1(即FF)。
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