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Unable to open file using fopen()

This is a discussion on Unable to open file using fopen() within the C Programming forums, part of the General Programming Boards category; I have following piece of code: Code: #define MAX_BYTES_LINE 100 // Main Program starts here //int main(int argc,char *argv[]) int ...

  1. #1
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    Unable to open file using fopen()

    I have following piece of code:

    Code:
    #define MAX_BYTES_LINE        100
    
    // Main Program starts here
    
    //int main(int argc,char *argv[])
    int main()
    {
    	char **ptdata,filename[40],count[10];
    	int cnt=2,i;
    	FILE *pFile;
    
    	/*if((argv[1] == NULL)&&(argv[2] == NULL))
    	{
    		printf("ERROR: Insufficient info \n");
    		return 1;
    	}
    
    	//Copy command line strings
    	strcpy(filename,argv[1]);
    	strcpy(count,argv[2]);
    	cnt = atoi(count);
    	printf("Filename : %s count :%s , count :%d",filename,count,cnt);*/
    	
    	strcpy(filename,"noop.txt"); //Assigning the filename
    
    	//Allocate memory
    	ptdata = malloc(cnt*MAX_BYTES_LINE*sizeof(char *));
    	if(ptdata == NULL)
    	{
    		printf("ERROR:Insufficient Memory\n");
    		return 1;
    	}
    	for(i=0;i<(cnt*MAX_BYTES_LINE);i++)
    	{
    		ptdata[i] = malloc(20*sizeof(char));
    		if(ptdata[i] == NULL)
    		{
    			printf("ERROR:Insufficient Memory\n");
    			return 1;
    		}
    	}
    
    	//File open	
    	pFile = fopen(filename,"r+"); //Does open file with this
    	//pFile = fopen("noop.txt","r+"); //Works fine here
    	if(pFile == NULL)
    	{
    		printf("ERROR : File cannot be opened\n");
    		return 1;
    	}
    	
    	 //Read file content	
    	fread (ptdata[1],1,20,pFile);
    
    	printf("File content:%s",ptdata[1]);
    	
    
    	//Destructor
    	fclose(pFile);
    	for(i=0;i<(cnt*MAX_BYTES_LINE);i++)
    		free(ptdata[i]);
    	free(ptdata);
    
    	return 0;
    }
    1. Why can't open File ,when I pass a buffer containing the filename to fopen()


    Thanks

  2. #2
    - - - - - - - - oogabooga's Avatar
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    You should post the simplest program that demonstrates the problem. Also be sure it is able to compile, including all necessary headers.

    Here's a simplification of your code. Does it work for you? If not, then either the file doesn't exist or you're accessing the wrong directory.

    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main()
    {
    	char filename[40];
    	FILE *pFile;
    
    	strcpy(filename,"noop.txt");
    
    	pFile = fopen(filename,"r+");
    	if(pFile == NULL)
    	{
    		printf("ERROR : File cannot be opened\n");
    		return 1;
    	}
    
    	fclose(pFile);
    
    	return 0;
    }
    stahta01 likes this.

  3. #3
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    I agree your suggestion....... was in hurry......

    I am unable to open the file, But it works fine if i pass the file name directly to the function.

    what may be wrong in the higlighted code?

    Thanks in advance

  4. #4
    - - - - - - - - oogabooga's Avatar
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    Nothing seems to be wrong with the highlighted code.
    You didn't answer my question.
    Does the simplified program that I posted work for you?

  5. #5
    spurious conceit MK27's Avatar
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    Quote Originally Posted by sanddune008 View Post
    1. Why can't open File ,[B]when I pass a buffer containing the filename to fopen()
    Ask the system itself:

    Code:
    	pFile = fopen(filename,"r+"); //Does open file with this
    	if(pFile == NULL)
    	{
    		perror(filename);
    		return 1;
    	}
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  6. #6
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    @oogabooga.......Simplified ex worked!!!....

  7. #7
    Registered User hk_mp5kpdw's Avatar
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    How are you running the code? Within an IDE or from the command-line?
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  8. #8
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    Quote Originally Posted by sanddune008 View Post
    @oogabooga.......Simplified ex worked!!!....
    then probably something you are doing between the strcpy and fopen is corrupting filename. printf the filename after your mallocs and right before the fopen.

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