Question

我正在尝试将文件拆分为多个较小的文件。问题是如果大小（用户给出的）大于缓冲区，程序崩溃否则它工作正常。有人可以帮忙吗？这是代码：

char * buffer = (char *)malloc(400);
FILE *exsistingFile = fopen(filename,"rb"); 

do
{   

    /*reading from a file */    
    bytesRead = fread( buffer, sizeof( char ), size, exsistingFile );

    /*exits if its 0 */ 
    if (bytesRead == 0)
    {
        printf("The reading has finished or the file has no data inside\n");
        return 0;
    } 

    fileCount ++;
    sprintf (newFileName,"%s%04i",output,fileCount);


    /* opening the new file bye the name given by the user */   
    outputFile = fopen(newFileName,"w");



    /*checking whether the file is opened or not*/
     if ( !outputFile )
    {
        printf( "File %s cannot be opened for reading\n", filename );
        return E_BAD_DESTINATION; 
    }

    /*write to file from the buffer*/
    fwrite(buffer,sizeof(char),bytesRead,outputFile);

    /*closing the output file*/
    fclose(outputFile);


    } while ( bytesRead > 0 );

Answer 1

size_t currentSize = (size >= 400) ? 400 : size;
size -= currentSize;

然后只发送currentSize

Answer 2

那么，malloc是一个与用户提供的大小一样大的缓冲区吗？或者只读取和写入400字节的位，直到达到用户给出的大小。

char * buffer = (char *)malloc(400);
FILE *exsistingFile = fopen(filename,"rb"); 

do
{   
    fileCount ++;
    sprintf (newFileName,"%s%04i",output,fileCount);

    /* opening the new file bye the name given by the user */   
    outputFile = fopen(newFileName,"w");

    /*checking whether the file is opened or not*/
    if ( !outputFile )
    {
        printf( "File %s cannot be opened for writing\n", filename );
        return E_BAD_DESTINATION; 
    }

    int workSize = size;
    while (workSize)
    {
        int chunkSize = workSize > 400 ? 400 : workSize;

        /*reading from a file */    
        bytesRead = fread( buffer, sizeof( char ), chunkSize, exsistingFile );
        workSize -= bytesRead;

        /*exits if its 0 */ 
        if (bytesRead == 0)
        {
            printf("The reading has finished or the file has no data inside\n");
            return 0;
        } 

        /*write to file from the buffer*/
        fwrite(buffer,sizeof(char),bytesRead,outputFile);
    }

    /*closing the output file*/
    fclose(outputFile);

} while ( bytesRead > 0 );

这样的事情。除了一些错误，但你明白了。这是家庭作业吗？

Answer 3

如果size是用户输入，则应根据给定的输入分配缓冲区，而不是使用硬编码值。

如何在C中将文件拆分成多个文件？

3 个答案: