Linux下关于文件操作出现乱码的问题

[沉默的牧羊者]

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

#define infile "infile.dat"
#define outfile "outfile.dat"

sem_t f1;
sem_t f2;

void inputdata()
{
    int infd;
    char buf[50];

    if ((infd = open(infile, O_WRONLY | O_TRUNC | O_CREAT, 10700)) == -1)
    {
        printf("ERROR, OPEN READ FILE FAILED:%s \n", sys_errlist[errno]);
        exit(255);
    }

    printf("Please enter the data:\n");
    printf("(Ctrl+D ---- quit)\n");

    while(fgets(buf, sizeof(buf), stdin))
    {
        if (write(infd, buf, strlen(buf)) != strlen(buf))
        {
            printf("ERROR, WRITE FILE FAILED:%s \n", sys_errlist[errno]);
            exit(255);
        }
    }
    close(infd);

    sem_post(&f1);
}

void copydata()
{
    sem_wait(&f1);

    int infd, outfd;
    char buf[50];

    if ((infd = open(infile, O_RDONLY))==-1)
    {
        printf("ERROR, OPEN READ FILE FAILED:%s \n", sys_errlist[errno]);
        exit(255);
    }

    if ((outfd = open(outfile, O_WRONLY | O_TRUNC | O_CREAT, 10700))==-1)
    {
        printf("ERROR, OPEN WRITE FILE FAILED:%s \n", sys_errlist[errno]);
        exit(255);
    }

    int count;

    while((count = read(infd, buf, sizeof(buf))) > 0)
    {
        if (count != write(outfd, buf, count))
        {
            printf("ERROR, WRITE FILE FAILED:%s \n", sys_errlist[errno]);
            exit(255);
        }
    }

    close(infd);
    close(outfd);

    sem_post(&f2);
}


void showdata()
{
    sem_wait(&f2);

    int outfd;
    char buf[50];

    if ((outfd = open(outfile, O_RDONLY, 10700))==-1)
    {
        printf("ERROR, OPEN WRITE FILE FAILED:%s \n", sys_errlist[errno]);
        exit(255);
    }

    int count;

    printf("\nThe data in the file:\n");

    while((count = read(outfd, buf, sizeof(buf))) > 0)
    {
        printf("%s", buf);
    }

    close(outfd);
}

void main()
{
    pthread_t t1,t2,t3,t4;
    sem_init(&f1,0,0);
    sem_init(&f2,0,0);

    pthread_create(&t1,NULL, (void *)showdata, NULL);
    pthread_create(&t2,NULL, (void *)copydata, NULL);
    pthread_create(&t3,NULL, (void *)inputdata, NULL);

    pthread_join(t1,NULL);
}

我想问一下，我觉得这段程序已经没有问题了，但是最后一步读文件时，会出现上面标记的乱码，这是为什么？？

[自信男孩]

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

#define infile "infile.dat"
#define outfile "outfile.dat"

sem_t f1;
sem_t f2;

void inputdata()
{
    int infd;
    char buf[50];

    if ((infd = open(infile, O_WRONLY | O_TRUNC | O_CREAT, 10700)) == -1)
    {
        printf("ERROR, OPEN READ FILE FAILED:%s \n", sys_errlist[errno]);
        //printf("ERROR, OPEN READ FILE FAILED:%s \n", strerror(errno));
        exit(255);
    }

    printf("Please enter the data:\n");
    printf("(Ctrl+D ---- quit)\n");

    while(fgets(buf, sizeof(buf), stdin))
    {
        if (write(infd, buf, strlen(buf)) != strlen(buf)) {
            printf("ERROR, WRITE FILE FAILED:%s \n", sys_errlist[errno]);
            //printf("ERROR, WRITE FILE FAILED:%s \n", strerror(errno));
            exit(255);
        }
    }
    close(infd);

    sem_post(&f1);
}

void copydata()
{
    sem_wait(&f1);

    int infd, outfd;
    char buf[50];

    if ((infd = open(infile, O_RDONLY))==-1)
    {
        printf("ERROR, OPEN READ FILE FAILED:%s \n", sys_errlist[errno]);
        //printf("ERROR, OPEN READ FILE FAILED:%s \n", strerror(errno));
        exit(255);
    }

    if ((outfd = open(outfile, O_WRONLY | O_TRUNC | O_CREAT, 10700))==-1)
    {
        printf("ERROR, OPEN WRITE FILE FAILED:%s \n", sys_errlist[errno]);
        //printf("ERROR, OPEN WRITE FILE FAILED:%s \n", strerror(errno));
        exit(255);
    }

    int count;

    while((count = read(infd, buf, sizeof(buf))) > 0)
    {
        if (count != write(outfd, buf, count))
        {
            printf("ERROR, WRITE FILE FAILED:%s \n", sys_errlist[errno]);
            //printf("ERROR, WRITE FILE FAILED:%s \n", strerror(errno));
            exit(255);
        }
    }

    close(infd);
    close(outfd);

    sem_post(&f2);
}


void showdata()
{
    sem_wait(&f2);

    int outfd;
    char buf[50];

    if ((outfd = open(outfile, O_RDONLY, 10700))==-1)
    {
        printf("ERROR, OPEN WRITE FILE FAILED:%s \n", sys_errlist[errno]);
        //printf("ERROR, OPEN WRITE FILE FAILED:%s \n", strerror(errno));
        exit(255);
    }

    int count;

    printf("\nThe data in the file:\n");

    memset(buf, 0, sizeof(buf));    /*初始化缓存为0*/
    while((count = read(outfd, buf, sizeof(buf) - 1)) > 0)    /*防止读到的数据是50个字符，最后一个字符用于字符串结束标记 '\0' */
    {
        printf("count = %d\n", count);
        printf("%s", buf);
        memset(buf, 0, sizeof(buf));    /*初始化缓存为0*/
    }

    close(outfd);
}

int main(void)
{
    pthread_t t1,t2,t3,t4;
    sem_init(&f1,0,0);
    sem_init(&f2,0,0);

    pthread_create(&t1,NULL, (void *)showdata, NULL);
    pthread_create(&t2,NULL, (void *)copydata, NULL);
    pthread_create(&t3,NULL, (void *)inputdata, NULL);

    pthread_join(t1,NULL);

    return 0;
}

出现乱码，是字符串没有找到'\0',即字符串结束标记；需要对缓存在读之前做初始化操作（初始化为0， 0 值等于'\0')，另一个方面，若文件中的字符大于缓存长度，所以每次读取都最大读取缓存长度减1。

[沉默的牧羊者]

[沉默的牧羊者]

抱歉，图片传不上去，大概是出现了一个类似问号?的乱码

[赵4老师]

对电脑而言没有乱码，只有二进制字节；对人脑才有乱码。啊 GBK:0xB0 0xA1,Unicode-16 LE:0x4A 0x55,Unicode-16 BE:0x55 0x4A,UTF-8:0xE5 0x95 0x8A

void HexDump(char *buf,int len,int addr) {
    int i,j,k;
    char binstr[80];

    for (i=0;i<len;i++) {
        if (0==(i%16)) {
            sprintf(binstr,"%08x -",i+addr);
            sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
        } else if (15==(i%16)) {
            sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
            sprintf(binstr,"%s  ",binstr);
            for (j=i-15;j<=i;j++) {
                sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
            }
            printf("%s\n",binstr);
        } else {
            sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
        }
    }
    if (0!=(i%16)) {
        k=16-(i%16);
        for (j=0;j<k;j++) {
            sprintf(binstr,"%s   ",binstr);
        }
        sprintf(binstr,"%s  ",binstr);
        k=16-k;
        for (j=i-k;j<i;j++) {
            sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
        }
        printf("%s\n",binstr);
    }
}

//iconv_linux下字符集编码转换轻松实现
(1) iconv_t iconv_open(const char *tocode, const char *fromcode);
//此函数说明将要进行哪两种编码的转换,tocode是目标编码,fromcode是原编码,该函数返回一个转换句柄,供以下两个函数使用。
(2) size_t iconv(iconv_t cd,char **inbuf,size_t *inbytesleft,char **outbuf,size_t *outbytesleft);
//此函数从inbuf中读取字符,转换后输出到outbuf中,inbytesleft用以记录还未转换的字符数,outbytesleft用以记录输出缓冲的剩余空间。
(3) int iconv_close(iconv_t cd);
//此函数用于关闭转换句柄,释放资源。

//例子1: 用C语言实现的转换示例程序

/* f.c : 代码转换示例C程序 */
#include <iconv.h>
#define OUTLEN 255
main()
{
char *in_utf8 = "姝ｅ?ㄥ??瑁?";
char *in_gb2312 = "正在安装";
char out[OUTLEN];

/*unicode码转为gb2312码*/
rc = u2g(in_utf8,strlen(in_utf8),out,OUTLEN);
printf("unicode-->gb2312 out=%sn",out);
//gb2312码转为unicode码

rc = g2u(in_gb2312,strlen(in_gb2312),out,OUTLEN);
printf("gb2312-->unicode out=%sn",out);
}
/*代码转换:从一种编码转为另一种编码*/
int code_convert(char *from_charset,char *to_charset,char *inbuf,int inlen,char *outbuf,int outlen)
{
iconv_t cd;
int rc;
char **pin = &inbuf;
char **pout = &outbuf;

cd = iconv_open(to_charset,from_charset);
if (cd==0) return -1;
memset(outbuf,0,outlen);
if (iconv(cd,pin,&inlen,pout,&outlen)==-1) return -1;
iconv_close(cd);
return 0;
}
/*UNICODE码转为GB2312码*/
int u2g(char *inbuf,int inlen,char *outbuf,int outlen)
{
return code_convert("utf-8","gb2312",inbuf,inlen,outbuf,outlen);
}
/*GB2312码转为UNICODE码*/
int g2u(char *inbuf,size_t inlen,char *outbuf,size_t outlen)
{
return code_convert("gb2312","utf-8",inbuf,inlen,outbuf,outlen);
}

//例子2: 用C++语言实现的转换示例程序

/* f.cpp : 代码转换示例C++程序 */
#include <iconv.h>
#include <iostream>

#define OUTLEN 255

using namespace std;

// 代码转换操作类

class CodeConverter {

private:
iconv_t cd;
public:

// 构造
CodeConverter(const char *from_charset,const char *to_charset) {
cd = iconv_open(to_charset,from_charset);
}


// 析构
~CodeConverter() {
iconv_close(cd);
}


// 转换输出
int convert(char *inbuf,int inlen,char *outbuf,int outlen) {
char **pin = &inbuf;
char **pout = &outbuf;

memset(outbuf,0,outlen);
return iconv(cd,pin,(size_t *)&inlen,pout,(size_t *)&outlen);
}
};

int main(int argc, char **argv)
{
char *in_utf8 = "姝ｅ?ㄥ??瑁?";
char *in_gb2312 = "正在安装";
char out[OUTLEN];

// utf-8-->gb2312
CodeConverter cc = CodeConverter("utf-8","gb2312");
cc.convert(in_utf8,strlen(in_utf8),out,OUTLEN);
cout << "utf-8-->gb2312 in=" << in_utf8 << ",out=" << out << endl;

// gb2312-->utf-8
CodeConverter cc2 = CodeConverter("gb2312","utf-8");
cc2.convert(in_gb2312,strlen(in_gb2312),out,OUTLEN);
cout << "gb2312-->utf-8 in=" << in_gb2312 << ",out=" << out << endl;
}



二、利用iconv命令进行编码转换

iconv命令用于转换指定文件的编码,默认输出到标准输出设备,亦可指定输出文件。

用法： iconv [选项...] [文件...]

有如下选项可用:

输入/输出格式规范：
-f, --from-code=名称 原始文本编码
-t, --to-code=名称 输出编码

信息：
-l, --list 列举所有已知的字符集

输出控制：
-c 从输出中忽略无效的字符
-o, --output=FILE 输出文件
-s, --silent 关闭警告
--verbose 打印进度信息

-?, --help 给出该系统求助列表
--usage 给出简要的用法信息
-V, --version 打印程序版本号

例子:
iconv -f utf-8 -t gb2312 aaa.txt >bbb.txt
这个命令读取aaa.txt文件，从utf-8编码转换为gb2312编码,其输出定向到bbb.txt文件。

小结: Linux为我们提供了强大的编码转换工具,给我们带来了方便。