3-b-io.c

Linux下的C代码 实现了对Linux的文件系统的操作

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

void err_quit(char* msg);

int main(void)
{
	 FILE* fp;
	 char *buffer;
	 char c;
	 int i;
	 
	 if ((buffer = (char*)malloc(1024)) == NULL)
		  err_quit("malloc error");
	 
	 if ((fp = fopen("tempfile2", "w+")) == NULL)
		  err_quit("fopen error");
	 
	 for (i=1; i<=100; i++)
		  sprintf(buffer+strlen(buffer), "%d", i);
	 
	 if (fprintf(fp, "%s", buffer) < 0)
		  err_quit("fprintf error");

	 if (fseek(fp, 50, SEEK_SET) < 0)
		  err_quit("fseek error");
	 c = fgetc(fp);
	 printf("The 50th byte is: %c\n", c);

	 if (fseek(fp, 100, SEEK_SET) < 0)
		  err_quit("fseek error");
	 c = fgetc(fp);
	 printf("The 100th byte is: %c\n", c);

	 fclose(fp);

	 if(remove("tempfile2") < 0)
		  err_quit("remove error");
	 
	 return 0;
}

void err_quit(char* msg)
{
	 fprintf(stderr, msg);
	 exit(1);
}