Thread: I Cant input filename and its annoying

Anybody have any advice here ??

I would like to read a filename into my programme but it not working with the code below, theres no way i want to type the whole path or any part of the filepath in each time so i am appending the filename that the user inputs to the filepath i have already added to a char buffer.

when however i print the resulting string to screen it gives me the path without the '\\' between the directories and instead shows me '\' so is this why fopen() is then unable to open the filepath? and why is my string being changed like this? or in the background has it remained the same but clever ole C is printing it with the single backslash to show me the usual filepath format?, if that is the case why is it still failing??

any help much appreciated

Code:

FILE *NumData;
    
    
    char fName[200];
    char fPath[200] = "c:\\documents and settings\\601887741\\My Documents\\Desktop.FS\\Misc\\Programming\\";
   

   printf("Enter filename > ");
   scanf("%s", &fName);
   strcat(fPath,fName);

   NumData = fopen(fPath, "r");

Originally Posted by rogster001

Anybody have any advice here ??

I would like to read a filename into my programme but it not working with the code below, theres no way i want to type the whole path or any part of the filepath in each time so i am appending the filename that the user inputs to the filepath i have already added to a char buffer.

when however i print the resulting string to screen it gives me the path without the '\\' between the directories and instead shows me '\' so is this why fopen() is then unable to open the filepath? and why is my string being changed like this? or in the background has it remained the same but clever ole C is printing it with the single backslash to show me the usual filepath format?, if that is the case why is it still failing??

any help much appreciated

Code:

FILE *NumData;
    
    
    char fName[200];
    char fPath[200] = "c:\\documents and settings\\601887741\\My Documents\\Desktop.FS\\Misc\\Programming\\";
   

   printf("Enter filename > ");
   scanf("%s", &fName);
   strcat(fPath,fName);

   NumData = fopen(fPath, "r");

scanf("%s", &fName);
What is the & operator doing here ? Its an array and its automatically supposed to decompose into an address? Rest everything is fine and i dont see any problem

The compiler uses the '\' in string literals to signal a control character sequence (such as "\n"). So two of them are used to instruct the compiler to generate one, eg:

"\\\\\\" -> "\\\"

So the problem is elsewhere. Can you post a working (eg: compilable) example of the problem?

>> What is the & operator doing here ? Its an array and its automatically supposed to decompose into an address? Rest everything is fine and i dont see any problem

Ah, good eye.

The other problem is that you are blindly reading into your string and catting onto a fixed size buffer without any checking for going over the size of that buffer.

If the user inputs more text then you can fit into the 200 character buffer + the patch you have already in there, you will be getting undefined behavior.

you probably want to use fgets and strtol and strncat instead of strcat

Originally Posted by Sebastiani

The compiler uses the '\' in string literals to signal a control character sequence (such as "\n"). So two of them are used to instruct the compiler to generate one, eg:

"\\\\\\" -> "\\\"

So the problem is elsewhere. Can you post a working (eg: compilable) example of the problem?

>> What is the & operator doing here ? Its an array and its automatically supposed to decompose into an address? .

thanks for the advice, i am going to review this and see whats what, i dont understand the second part about &operator? i thought always used this with scanf, meaning 'read value input into address of...' you mean i should just write ("%s", fName) ?

Code:

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    FILE *NumData;
 
    
    char fName[200];
    char fPath[200] = "c:\\myfile.txt";
  
  
   
   printf("Enter filename |> ");
   scanf("%s", &fName);
   strcat(fPath,fName);
   
   NumData = fopen(fPath, "r");  
     
  system("PAUSE");	
  return 0;
}

Originally Posted by roaan

scanf("%s", &fName);
What is the & operator doing here ? Its an array and its automatically supposed to decompose into an address? Rest everything is fine and i dont see any problem

Hey good tip,,,it solved it! i got rid of the & realising why that made sense and done, thanks!