逐行读取C并存储在数组中

Question

我正在尝试从文件列表中读取文件名并将这些名称存储在 filenames[] 数组中。

const int NUMBER_OF_FILES = 100;//here please define number of files listed in 
char* filenames [NUMBER_OF_FILES];//will contain all the file names in the list provided in List_of_input_files.txt

int counter=0;
FILE *inputfilelist = fopen("List_of_input_files.txt", "r");
char line[256];


  while(fgets(line, sizeof(line), inputfilelist)){

    filenames[counter]=line;    
    printf("%s counter: %d\n\n\n", filenames[counter], counter);
    counter++;
  }


//**************PROBLEM IS HERE***************

printf("\n\n\n\n%s Counter: 3 ", filenames[2]);// this is only to test what is inside this filename stored

fclose(inputfilelist);

输出是：

File1.txt
 counter: 0


File2.gif
 counter: 1


File3.bat
 counter: 2


File4.xml
 counter: 3


File5
 counter: 4


File6.7z
 counter: 5


File7.xlsx
 counter: 6






File7.xlsx
  Counter : 3

问题是最后一个文件名应该是 File3.bat 但不知何故它不是。 它总是显示行中的最后一个文件，即 File7.xlsx。

也许这是我正在做的一个愚蠢的错误，并且没有清楚地看到它或其他什么。我是c新手，所以我不确定。请帮忙！

已经改进并添加了要求的东西。

Answer 1

这一行

filenames[counter]=line; 

没有做你想做的事；它将line 缓冲区的地址 复制到filenames[counter]；你所有的filenames[i]指向line，所以当你打印filenames[2]时，它会打印出读入line的最后一个东西。

如果您想将line 的内容复制到filenames[counter]，您需要使用malloc 或calloc 分配内存来保存副本，然后复制内容使用strcpy（或使用strdup，如果有的话）：

filenames[counter] = malloc( strlen( line ) + 1 );
if ( filenames[counter] )
  strcpy( filenames[counter], line );

或

filenames[counter] = strdup( line ); // if you have strdup available;
                                     // it's not a standard function

完成后，您需要free 每个filenames[i]。

或者，您可以将filenames 数组声明为char 的二维数组：

char filenames[NUMBER_OF_FILES][256];

直接读入数组：

fgets(filenames[counter], sizeof(filenames[counter]), inputfilelist))

Answer 2

你必须分配内存来存储多个文件名。

const int NUMBER_OF_FILES = 100;//here please define number of files listed in
const int MAX_FILE_NAME_SIZE = 50;
char filenames[NUMBER_OF_FILES][MAX_FILE_NAME_SIZE];//will contain all the file names in the list provided in List_of_input_files.txt

int counter=0;
FILE *inputfilelist = fopen("List_of_input_files.txt", "r");
char line[256];


  while(fgets(line, sizeof(line), inputfilelist))
  {

    //filenames[counter]=line;
    strcpy(filenames[counter],line);
    printf("%s counter: %d\n\n", filenames[counter], counter);
    counter++;
  }


//**************PROBLEM IS HERE***************

printf("\n\n\n%s Counter: 3 ", filenames[2]);// this is only to test what is inside this filename stored

fclose(inputfilelist);