c - 在 C 中使用 read() 系统调用来读取整数

Question

我必须使用从文件中读取的一次来构建一个包含字符、整数和 float 的结构。我可以很好地读取字符，但读取整数时遇到问题

CountryData ReadingFile(Directory* CountryDirectory,int SortedCountryData,char *Code,int NumberofCountries)
{
    int Location,i;  // Will store Location in array and location in bytes
    char Buff[40]; //Buffer the size of the stuct
    char Tok[25];
    CountryData Country;
    off_t offset;  //Offset value
    ssize_t count;

    Location = BinarySearch(CountryDirectory,Code,0,NumberofCountries-1); //Findlocation in array
    Location =CountryDirectory[Location].Offset; //Find location in bytes
    offset = lseek(SortedCountryData, Location, SEEK_SET); //Seek to location in file
    count = read(SortedCountryData,Buff,40); //Read file

     //Data in Buff should be Code[4],Name[25],int,float

    for(i=0;i<4;i++)//Get code
    {
    Tok[i] = Buff[i];
    }
    strncpy(Country.Code,Tok,sizeof(Country.Code));//Copy Code

    for(i=0;i<25;i++)//Get Name
    {
    Tok[i]=Buff[i+4];
    }
    strncpy(Country.Name,Tok,sizeof(Country.Name));//Copy Name

        //This is where I try to read the int
    char INTEGER[4];
    for(i=0;i<4;i++) //Read an int
    {
        INTEGER[i]=Buff[33+i];
    }
    int A =(int)INTEGER;
    printf("Tok: %d",A);

    return(Country);


}

Answer 1

我相信@slugonamission关于指针问题是正确的，但如果我正确理解问题，int将作为int存储在文件中，而你处理char数组的原因是你被迫从您阅读的方式。

为此尝试 memcpy。还要注意字节序问题。

int A;
memcpy(&A, Buff + 33, 4 * sizeof(char))