C函数_filelength函数了解

_filelength()---->Gets the length of a file.

原型：

fd:Target the file descriptor.

取文件长度字节数.

Both _filelength and _filelengthi64return the file length, in bytes, of the target file associated withfd

DEMO1:

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <io.h>
int main(void)
{
	FILE *fp;
	long file_handle;
	char buffer[]="0123456789";
	/*create a file containing 10 bytes*/
	if((fp=fopen("hgj.txt","wb+"))==NULL)
	{
		fprintf(stderr,"ERROR!
");
		getchar();getchar();
		return -1;
	}
	fwrite(buffer,strlen(buffer),1,fp);
	fseek(fp,0,SEEK_SET);     //疑惑，这里不加fseek，最后结果是0
	/*display the size of file*/
	printf("file length in bytes:%ld 
",_filelength(_fileno(fp)));
	fclose(fp);
	system("pause");
	return 0;
}

【FROM MSDN && 百科】