C/C++读取分析文件

1、读取文件，逐行读取的函数

void read_line(FILE* fp,char* line)
{
    if (fp == NULL)//判断指针是否为空
    {
        return;
    }
    int i = 0;

    char ch = fgetc(fp);
    while(ch != '\n' && !feof(fp))
    {
        line[i] = ch;
        i++;
        ch = fgetc(fp);
    }
    line[i] = '\0';
    return;
}

  或者可以用getline()函数读取

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    cout<<"-----------------------------------------------\n";
    cout<<"File Begin"<<endl;
    
    //开始处理文件

    
    fstream istrm("Company.js");
    fstream ostrm("Company.txt");
    string fstr;



    int nBeginPos;
    int nEndPos;
    int nLen = 0;
    string strsub;
    
    for(int i = 0;i < 10;i++)
    {
        getline(istrm,fstr);
        //cout<<fstr<<endl;


        nBeginPos = fstr.find("id");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<'|';

        nBeginPos = fstr.find("CnName");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<'|';

        nBeginPos = fstr.find("CNaddress");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<'|';

        nBeginPos = fstr.find("phone");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<'|';


        nBeginPos = fstr.find("fax");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<'|';

        nBeginPos = fstr.find("Email");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<'|';

        //nBeginPos = fstr.find("Homepage");
        //nEndPos = fstr.find_first_of(',',nBeginPos);
        //nLen = nEndPos - nBeginPos;
        //strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        //ostrm<<strsub<<',';


        nBeginPos = fstr.find("Website");
        nEndPos = fstr.find_first_of(',',nBeginPos);
        nLen = nEndPos - nBeginPos;
        strsub = fstr.substr(nBeginPos,nLen);
        //cout<<"-----------------------------------------------\n";
        //cout<<strsub<<endl;
        ostrm<<strsub<<endl;
    }
    
    /*
    FILE *fp;
    fp=fopen("Company.js","r");
    char buff[1024*10];
    memset(buff,0,1024*10);

    read_line(fp,buff);
    cout<<buff<<endl;*/





    cout<<"-----------------------------------------------\n";
    cout<<"File End"<<endl;


    system("pause");

    return 0;
}

读取文件的几种方式：

void file1()
{
    char ch;
    int i;
    char s[]={'A','B','\n','C'};
    FILE *fp1,*fp2;
    if((fp1=fopen("test1.txt","wt"))==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    if((fp2=fopen("test2.txt","wb"))==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    for(i=0;i<4;i++)
    {
        fputc(s[i],fp1);    //以文本方式向文件中写入数据 
        fputc(s[i],fp2);    //以二进制方式向文件中写入数据 
    }
    fclose(fp1);
    fclose(fp2);
    if((fp1=fopen("test1.txt","rt"))==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    if((fp2=fopen("test1.txt","rb"))==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    ch=fgetc(fp1);
    while(!feof(fp1))    //以文本方式从文件中读取数据 
    {
        printf("%02X",ch);
        ch=fgetc(fp1);
    }
    printf("\n");
    ch=fgetc(fp2);
    while(!feof(fp2))   //以二进制方式从文件中读取数据
    {
        printf("%02X",ch);
        ch=fgetc(fp2);
    }
    printf("\n");
    fclose(fp1);
    fclose(fp2);
}

void file2()
{
    int n;
    FILE* fp;

    if((fp=fopen("test.txt","a"))==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    n=ftell(fp);     //得到此时fp所处位置距文件首的偏移字节数
    printf("%d\n",n);
    fputs("test",fp);
    n=ftell(fp);
    printf("%d\n",n);
    fclose(fp);
}

void file3()
{
    int ch;
    int n;
    FILE *fp;
    if((fp=fopen("test.txt","r+"))==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    fseek(fp,1L,0);  //将fp移动到距文件首1字节的位置    
    ch=fgetc(fp);
    printf("%c\n",ch);
    //rewind(fp);
    fseek(fp,1L,0);
    fputs("test",fp);
    ch=fgetc(fp);
    printf("%c\n",ch);
    fclose(fp);
}

测试文件的几个函数例子

int main(void)
{

    char szBuff[1024] = "file test";

    cout<<szBuff<<endl;

    
    FILE *fp;
    //写文件
    fp=fopen("acctinfo.txt","wt+");

    if(fp==NULL)
    {
        printf("can not open file\n");
        exit(0);
    }
    cout<<"-------------------------------------------------------------------------------"<<endl;
    //fputs(szBuff,fp);//往文件里写单个字符
    fwrite(szBuff,strlen(szBuff),1,fp);//往文件里写数据


    //读文件
    /*fp=fopen("acctinfo.txt","r");
    char buff[1024];
    memset(buff,0,1024);

    int nLen = ftell(fp);

    int i = 0;
    while(!feof(fp))
    {
        read_line(fp,buff);
        cout<<buff<<endl;
        //i++;
        //if (i == 10)
        //{
        //    break;
        //}
    }
    cout<<i<<endl;
    */

    /*
    fseek(fp, 0L, SEEK_END);
    fseek(fp,0,SEEK_SET);//将文件指针移回首部

    rewind(fp);//将文件指针放到开头
    fgets(buff,1024,fp) ;
    cout<<buff<<endl;

    fread(buff,strlen(szBuff),1,fp);

    cout<<buff<<endl;

    fclose(fp);//关闭文件
    */

    /*
    ifstream   in("acctinfo.txt");  
    string   line;  
    getline(in,   line);  
    cout<<line<<endl; 
    */
    system("pause");

    return 0;
}