Weird error

This is a discussion on Weird error within the C Programming forums, part of the General Programming Boards category; today i made FILE I/O but i wanted the user to press his like if he want name lol.txt it ...

  1. #1
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    Weird error

    today i made FILE I/O but i wanted the user to press his like if he want name lol.txt it will make it as lol.txt i made it work but it only accept 10 char array when i change the fgets to lets say 100 it doesnt want to :S i dunno whats with this error
    Code:
    #include "inc.h"
    int main(void)
    {
        char name[100];
        FILE*fptr;
        printf("Where do u wanna save your file  ??");
        fputs("PLease enter your file name: ",stdout);
        fgets(name,10,stdin);
        fptr=fopen(name,"w");
        if(fptr==NULL)
    {
                      fprintf(stderr,"Coudlnt Access %s - because %s",name,sys_errlist[errno]);
                      exit(1);
    }
    fprintf(fptr," ");
    getchar();
    fclose(fptr);
        return 0;
    }

  2. #2
    Kernel hacker
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    Let me guess - your filename is 9 characters long, and since your code doesn't remove the newline, it leaves the newline in the input buffer when you use 10, but when you put 100, you get a newline on the end of the filename, which makes the filename invalid, and thus the fopen() fails. That is of course just a guess.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
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    coz invalid arguments ??why is that and why have i got error opening ??

  4. #4
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    thanks i fixed it now
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    int main(void)
    {
        char name[100];
        FILE*fptr;
        int i;
        printf("Where do u wanna save your file  ??");
        fputs("PLease enter your file name: ",stdout);
        fgets(name,100,stdin);
        for(i=0;i<100;i++)
        {
                          if(name[i]=='\n')
                          {
                                           name[i]=NULL;
                                           }
    }
        fptr=fopen(name,"w");
        if(fptr==NULL)
    {
                      fprintf(stderr,"Coudlnt Access %s - because %s",name,sys_errlist[errno]);
                      getchar();
                      exit(1);
    }
    fprintf(fptr," ");
    getchar();
    fclose(fptr);
        return 0;
    }
    it compiles fine with msv6 but with dev i get this error
    assignment makes integer from pointer without a cast

    i dunno why

  5. #5
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by lolguy View Post
    it compiles fine with msv6 but with dev i get this error
    assignment makes integer from pointer without a cast

    i dunno why
    Because NULL is a pointer type, and you are assigning it to a character. Instead of NULL use '\0' or just 0.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  6. #6
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    Quote Originally Posted by brewbuck View Post
    Because NULL is a pointer type, and you are assigning it to a character. Instead of NULL use '\0' or just 0.
    thanks

  7. #7
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    And writing code that loops through the entire string when there are nice functons like "strchr" that finds a character in the string as a standard function seems like asking for trouble.

    Also, you should probably use MAX_PATH instead of 100 - as that is the value of the max length of a (non-redundant) path+filename. Of course, if you throw in a load of . and .. in the filename, you can make it infinitely long, since you can append as many "/foo/../foo/.." as you like and still be in the same place.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  8. #8
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    Quote Originally Posted by matsp View Post
    And writing code that loops through the entire string when there are nice functons like "strchr" that finds a character in the string as a standard function seems like asking for trouble.

    Also, you should probably use MAX_PATH instead of 100 - as that is the value of the max length of a (non-redundant) path+filename. Of course, if you throw in a load of . and .. in the filename, you can make it infinitely long, since you can append as many "/foo/../foo/.." as you like and still be in the same place.

    --
    Mats
    yah i was gonna change defines i ill do in end coz this is base of my program but thanks for the tip for strchr it sounds like cool function i ill look into it now

  9. #9
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    i m trying to do the other part of the code but i get compiler error i think coz i m lil bad with multi dimensional arrays
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    int main(void)
    {
        char name[10][100];//we got 10 strings and each of them are length 100
        FILE*fptr;
        int i;
        char yesno;
    	int x;
    	for(i=0;i<10;i++)
    	{
                         printf("enter your Name of the file num %d",i+1);
                         scanf("%s",&name[i]);
                         fptr=fopen(name[i],"w");
        if(fptr==NULL)
    {
                      fprintf(stderr,"Coudlnt Access %s - because %s",name,sys_errlist[errno]);
                      getchar();
                      exit(1);
    }
                         printf("Do you wanna continue ??");
                         scanf("%c",&yesno);
                         if(yesno=='N' || yesno=='n')
                         {
                                       break;
                                  }
    	}
        for(x=0;x<100;x++)
        {
                          if(name[x]=='\n')
                          {
                                           name[x]=0;
                                           }
    }
    fprintf(fptr," ");
    getchar();
    fclose(fptr);
        return 0;
    }

  10. #10
    and the hat of int overfl Salem's Avatar
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    Your crappy indentation is still vinegar, and not honey.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  11. #11
    CSharpener vart's Avatar
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    scanf("%s",&name[i])
    name[i] is already pointer to char - no need to add &

    %s reads till the first white space - name could contain spaces
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  12. #12
    C++まいる!Cをこわせ!
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    Apart from the sucky indentation...
    Scanf woes
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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