C/C++编程：文件输入输出流

￡神魔★判官ぃ 2022-05-21 13:14 244阅读 0赞

## 应用 ##

## 压缩文件的复制 ##

### C版本 ###

#include <unistd.h>
    #include <stdio.h>
    #include <stdlib.h>
    
    #define MAXLINE 1024 * 3
    
    int main () {
        long total = 0, length = 0;
        FILE* src = NULL, *dst = NULL;
        char * buffer;
    
        // “rb+”　　　　　  读写打开一个二进制文件
        // wb+   打开或建立一个二进制文件
        //     -用”w”打开文件时，若文件不存在，则创建，若存在，则将其删除，再创建一个文件
        src = fopen("/home/oceanstar/CLionProjects/acl_redis.tar.gz", "rt+");
        dst = fopen("/home/oceanstar/copy.tar.gz", "wb+");
        if(src == NULL || dst == NULL){
            perror("fopen error");
            return -1;
        }
    
        buffer = (char*) malloc (sizeof(char)*MAXLINE);
        if (buffer == NULL) {
            fputs ("Memory error",stderr);
            exit (2);
        }
    
    
        fseek(src,0L,SEEK_END);
        length=ftell(src);
        rewind(src);
        printf("src has [%ld] characters...", length);
    
        while (true){
            fseek(src,total,SEEK_SET);
            int t = fread(buffer, 1, MAXLINE, src);
            fwrite (buffer ,1, t, dst);
    
            total = total + t;
            if(total == length){
                break;
            }
        }
        fclose(src);
        fclose(dst);
        free(buffer);
        return 0;
    }

### C++版本 ###

// copy a file using file stream buffers
    #include <fstream>      // std::filebuf, std::fstream
    #include <cstdio>       // EOF
    #include <iostream>
    
    #define MAXLINE 1024 * 3
    
    int main () {
        long total = 0, length = 0;
        char * buffer = new char [MAXLINE];
        std::fstream src,dest;
    
        src.open ("/home/oceanstar/CLionProjects/acl_redis.tar.gz",   std::fstream::in | std::fstream::out | std::fstream::binary);
        dest.open ("/home/oceanstar/copy.tar.gz",    std::fstream::out);   // out: 文件不存在就创建
    
        src.seekg (0, std::fstream::end);
        length = src.tellg();
        std::cout << "src  has [ " << length << " ]characters... ";
    
        
        while (true){
            src.seekg(total, std::fstream::beg);
            src.read (buffer,MAXLINE);
            dest.write(buffer, src.gcount());
    
            total = total + src.gcount();
            if(total == length){
                break;
            }  // 34729142
        }
    
        dest.close();
        src.close();
        delete [] buffer;
    
        return 0;
    }