Linux学习之嵌入式Linux编程文件IO（C语言版）

一、文件IO常用函数

1.open

2.write

3.read

示例代码：

#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>typedef struct Student
{char _name[20];char _schoolnumber[20];
}Student;
int main()
{int fd;int rd;int wr_len_name = 0;int wr_len_schoolnumber=0;int sumstr=0;int flag=1;int str1;int str2;int str3;char str_1[]={"My name is:"};char str_2[]={"My schoolnumber is:"};char str_3[]={"    "};char str_read[256];	fd = open("Schoolnumber.txt", O_CREAT | O_RDWR|O_APPEND, 0777);if (fd < 0){printf("Open file schoolnumber.txt failuse!\n");return -1;}printf("Open file schoolnumber.txt success!\n");while(flag!=-1&&flag==1){Student* add = (Student*)malloc(sizeof(Student));printf("Please enter your name:\n");scanf("%s", add->_name);printf("Please enter your student number:\n");scanf("%s", add->_schoolnumber);printf("Start write,please wait...\n");strcat(add->_schoolnumber,"\r\n");str1=write(fd,str_1,strlen(str_1));wr_len_name = write(fd, add->_name, strlen(add->_name));str3=write(fd,str_3,strlen(str_3));str2=write(fd,str_2,strlen(str_2));wr_len_schoolnumber = write(fd, add->_schoolnumber, strlen(add->_schoolnumber));printf("Do you want to continue typing?,Enter - 1 to exit, 1 to continue...\n");scanf ("%d",&flag);sumstr+=strlen(str_1)+strlen(str_2)+strlen(str_3)+strlen(add->_name)+strlen(add->_schoolnumber);}if (wr_len_name&&wr_len_schoolnumber){	printf("Write to file schoolnumber.txt success!\n");printf("Wrile length is:[%d]!\n",sumstr);}else{printf ("write to file schoolnumber failure...\n");}close(fd);printf("The contents read from the file are:\n");printf("______________________________________________________________________\n");rd=open("Schoolnumber.txt", O_RDONLY|O_APPEND, 0444);read(rd,str_read,sumstr);for(int i=0;i<sumstr;++i)
{printf("%c",str_read[i]);
}printf("\n");printf("______________________________________________________________________\n");close(fd);
return 0;
}