linux下C 大家帮我看看代码错哪里了 为什么结构体里的内容不能写到文件中呢

[liyuzhu_1984]

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



struct syster
{
	char SysID[5];
	char SysName[19];
	char SubSysID[19];
	char SubSysName[22];
	int NodeID;
	char NodeUpTime[30];
	char NodeDescr[20]; 
}sys={"k1","Host","009","HostMonitor",2,"2005-04-01","node"};

char buf[100];

int WriteStruFile(char *ptrFileName, struct syster *ptrStr)
{
	int fd;
	int length;
	int res;

	memset(buf,0,sizeof(buf));
	sprintf(buf,"[SysID]=%s\n",ptrStr->SysID);
	printf("%s\n",buf);
	if(fd = open(ptrFileName,O_WRONLY | O_CREAT | O_TRUNC, S_IREAD | S_IWRITE) == -1)
	{
		printf("open file failed!!");
		return -1;
	}
	length = strlen(buf);
	if ((res = write(fd, buf, length)) != length) 
	{
		printf("Error writing to the file.\n"); 
		exit(1); 
	}
	close(fd);  
}

int main()
{
	WriteStruFile("/root/changye/wwww/SysTable",&sys);

	return 0;  
}

[Wolf0403]

/root/changye/wwww

这些目录都存在么？

[liyuzhu_1984]

存在

[hanb99]

不知道，太怪了
如果写成这样就可以保存了

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

struct syster
{
    char SysID[5];
    char SysName[19];
    char SubSysID[19];
    char SubSysName[22];
    int NodeID;
    char NodeUpTime[30];
    char NodeDescr[20]; 
}sys={"k1","Host","009","HostMonitor",2,"2005-04-01","node"};

char buf[100];

int WriteStruFile(char *ptrFileName, struct syster *ptrStr)
{
    int fd;
    int length;
    int res;

    memset(buf,0,sizeof(buf));
    sprintf(buf,"[SysID]=%s\n",ptrStr->SysID);
    printf("%s\n",buf);
    fd = open(ptrFileName,O_WRONLY | O_CREAT | O_TRUNC, S_IREAD | S_IWRITE);

    length = strlen(buf);
    res = write(fd, buf, length);
    close(fd);  

}

int main()
{
   WriteStruFile("/home/whf/aaa",&sys);//这个文件名是我自己的


    return 0;  
}

真怪，把所有的if去掉，OK
不明白

[hij333]

if((fd = open(ptrFileName,O_WRONLY | O_CREAT | O_TRUNC, S_IREAD | S_IWRITE) )== -1)
{
printf("open file failed!!");
return -1;
}


上边的fd应该加上括号

[hanb99]

而且如果有if的时候fd的值为0,会在屏幕上输出两次[SysID]=k1
如果去掉if，fd的值为3,只在屏幕上输出一次[SysID]=k1
我想会不会是因为fd的值为0所以程序把它当做标准输出，直接写到屏幕上了，没有写进文件，但它为什么会是0呢

[linuxsir2007]

Node n;
.....

FILE* fp;
    fp=fopen("1.dat","wb");
    if(fp!=NULL)
    {
        fwrite(&n,sizeof(Node),1,fp);

    }
    fclose(fp);

[hanb99]

[Quote=引用 4 楼 hij333 的回复:]
if((fd = open(ptrFileName,O_WRONLY ¦ O_CREAT ¦ O_TRUNC, S_IREAD ¦ S_IWRITE))== -1)
{
printf("open file failed!!");
return -1;
}


上边的fd应该加上括号
[/Quote]
呵呵，高人！！！

[hanb99]

fd的0是==的值，I SEE 了

[liyuzhu_1984]

4楼正解 是我疏忽了 结贴了哈

[123ppmove]

运算符优先级问题啊；