loop doesn't read files

Hello all: My work need to read files into arrays. In the past, only
several files,I set a file pointer and used fscanf with following codes
(supose each file only has 3-number in three lines):

Code:

          if((fp=fopen("file1.txt", "r"))==NULL) 
          {cout<<"can not open file 1"<<endl;);
           return;
          }
          for(int i=0; i<3; i++) fscanf(fp,"%f", &arr[0][i]); //read file1    
          
          if((fp=fopen("file2.txt", "r"))==NULL) 
          {cout<<"can not open file 2"<<endl;);
          return;
          }
          for(i=0; i<3; i++) fscanf(fp,"%f", &arr[1][i]); //read file2

When running the above codes, the files are in the same folder of cpp
source codes. The above codes work well except reading files one by one.

Now the number of files become more. I tried to use loop to avoid one
by one. But failed! The following is the codes.

Code:

         char textfile[3][10]={"file1.txt","file2.txt","file3.txt"};
         for(j=0; j<3; j++)
	 {
           if((fp=fopen("textfile[j]", "r"))==NULL) 
	   {cout<<"can not open file "<<j<<endl;
            return;
	   }
         for(i=0; i<3; i++) fscanf(fp,"%f", &arr[j][i]); 	   
        }

This codes also can pass compiling and linking, but the result
of excuting is allways: "can not open file[0]"!

Clearly, "file1.txt" can not be changed to "textfile[0]", although
textfile[0]=file1.txt;"file2.txt" can not be changed to "textfile[1]",
although textfile[1]=file2.txt;..... Why?

Who can help me with the problem? Or suggest me other good way for
reading files.

This is more C than C++. You should be using fstreams, and I'm by no means any sort of pro in C File I/O, but isn't there a function you should be calling in each loop. Anyway, forget about that, you use iostreams, you should be using fstreams.

Originally Posted by Yumin

Code:

         char textfile[3][10]={"file1.txt","file2.txt","file3.txt"};
         for(j=0; j<3; j++)
	 {
           if((fp=fopen("textfile[j]", "r"))==NULL) 
	   {cout<<"can not open file "<<j<<endl;
            return;
	   }
         for(i=0; i<3; i++) fscanf(fp,"%f", &arr[j][i]); 	   
        }

This codes also can pass compiling and linking, but the result
of excuting is allways: "can not open file[0]"!

"textfile[j]" is a string, not a variable. Try

Code:

if ((fp = fopen(textfile[j], "r")) == NULL)

Also, formatting with more whitespace would make the code easier to read:

Code:

char textfile[3][10] = {"file1.txt", "file2.txt", "file3.txt"};
for (j = 0; j < 3; j++)
{
    etc...

Hi Waltp:

Thank you for the suggestion, it works.

By the way how to put all the files into one separate
folder, say "ABC". You know they are now put in the same
folder of source codes.

Add the directory (the proper term for folder ) to the filename:

Code:

char textfile[3][10]={"ABC\\file1.txt","ABC\\file2.txt","ABC\\file3.txt"};

Use \\ to add a single backslash since it's read as an ESCape character.

Hi WaltP:

I tried your suggestion:

Code:

    char textfile[3][10]={"ABC\\file1.txt","ABC\\file2.txt","ABC\\file3.txt"};

repeatedly, it doesn't work! It always prompts:

error C2117: 'abc\file1.txt' : array bounds overflow

Where put the folder "ABC", parellel/same-level to source-code-folder or
sub-folder of of it?

Have you tested? Sorry bothering you!