Question

这是来自getline手册页的代码片段，效果非常好。

while ((read = getline(&line, &len, fp)) != -1) {
    printf("Retrieved line of length %zu :\n", read);
    printf("%s", line);
    printf("%s", line[0]);
}

但是，当我尝试从行变量中访问单个字符时，例如：

Declare @SQL varchar(max) = ''
Set @SQL = Stuff((Select Distinct ','  +QuoteName('C'+cast(RN as varchar(25))) 
                                   +','+QuoteName('P'+cast(RN as varchar(25)))
                   From (Select Distinct RN=Row_Number() over (Order By Pays) From YourTable) A  
                   Order by 1 For XML Path('')),1,1,'') 

Set @SQL = '
Select ' + replace(replace(@SQL,'[P','Pays=[P'),'[C','Count=[C') + '
From (
        Select B.*
         From  (
                Select *,RN = Row_Number() over (Order By Pays)
                 From  YourTable
               ) A
         Cross Apply (values (''P''+cast(A.RN as varchar(25)),A.Pays)
                            ,(''C''+cast(A.RN as varchar(25)),cast(A.Count as varchar(50)))
                     ) B (Item,Value)
     ) A
 Pivot (max(value) For [Item] in (' + @SQL + ') ) p'
Exec(@SQL);

我收到了分段错误（核心转储）错误。

Answer 1

此：

printf("%s", line[0]);

不是如何打印字符。 %s告诉printf()期望C中的字符串是char数组（相当于指向char的指针）。因此，char被视为字符串的地址，导致分段错误。

这是你想要做的：

printf("%c", line[0]);

运行getline后无法读取单个字符

1 个答案: