Linux C/C++之mycat（包含标准IO和文件IO）

标准IO

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

#define READ_LEN 1024

int main(int argc, char **argv)
{
	if(argc < 2)
	{
		fprintf(stderr,"%s:Missing parameters\n",argv[0]);
		exit(1);
	}

	FILE * file = NULL;
	file = fopen(argv[1],"r");
	if(file == NULL)
	{
		fprintf(stderr,"fopen():%s",strerror(errno));
		exit(2);
	}

	char read_buf[READ_LEN] = {0};
	int read_ret = 0;
	while(1)
	{
		read_ret = fread(read_buf,1,READ_LEN,file);
		if(read_ret <= 0)
		{
			if(ferror(file) != 0)
				fprintf(stderr,"fread error!\n");
			break;
		}
		printf("%s",read_buf);
	}
	fclose(file);
	exit(0);
}

文件IO

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#define READ_LEN 1024

int main(int argc, char **argv) {
  if (argc < 2) {
    fprintf(stderr, "%s:Missing parameters\n", argv[0]);
    exit(1);
  }

  int fd = 0;
  fd = open(argv[1], O_RDONLY);
  if (fd < 0) {
    fprintf(stderr, "open():%s", strerror(errno));
    exit(2);
  }

  char read_buf[READ_LEN] = {0};
  int read_ret = 0;
  while (1) {
    read_ret = read(fd, read_buf, READ_LEN);
    if (read_ret > 0) {
      printf("%s", read_buf);
    }
    if (read_ret == 0)
      break;
    if (read_ret == -1) {
      fprintf(stderr, "read():%s", strerror(errno));
      break;
    }
  }
  close(fd);
  exit(0);
}