c - 从文件中读取整数

Question

使用 feof() 函数，在我的输出文件中，我将最后一个值打印了两次。我怎样才能避免这种情况？我的输出应该是

1261513

and i have

126151313

Thank you!

while(!feof(pfile1))
{       
    sum=0;
    fscanf(pfile1,"%d%d%d",&choice,&day,&val);
    if(choice==0)
    {
        i=day-1;
        a[i]=a[i]-val;
    }
    else if(choice==1)
    {
        for(i=day-1;i<=val-1;i++)
        {
            sum=sum+a[i];

        }
        fprintf(pfile2,"%d\n",sum);     
    }
}

Answer 1

一个选项是检查 fscanf 的返回值:

On success, the function returns the number of items successfully read. This count can match the expected number of readings or be less -even zero- in the case of a matching failure. In the case of an input failure before any data could be successfully read, EOF is returned.

所以，像这样:

if( fscanf(pfile1,"%d%d%d",&choice,&day,&val) <= 0 )
{
    break;
}

另一个选项是在执行fscanf 之后检查feof。例如:

if( feof( pfile1 ) )
{
    return; // or something
}
do
{
    // the same loop body
}
while( ! feof( pfile1 ) );