一 标准库 fseek 至尾部 读取ftell返回

#include <stdio.h>int main(int argc, char** argv)
{char* filename=argv[1];FILE* fp = fopen(filename, "r");long int size ;fseek(fp, 0, SEEK_END);size = ftell(fp);printf("%s size is %ld\n",filename,size);fclose(fp);return 0;
}

二 stat读取文件信息

#include <stdio.h>
#include <sys/stat.h>int main(int argc, char** argv)
{char* filename=argv[1];struct stat fstat;stat(filename,&fstat);printf("%s size is %ld\n",filename,fstat.st_size);return 0;
}

三 lseek 和fseek差不多

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>int main(int argc, char** argv)
{char* filename=argv[1];int fd = open(argv[1],O_RDONLY);long int size = 0;size = lseek(fd,0,SEEK_END);printf("%s size is %ld\n",filename,size);close(fd);return 0;
}