hi i am new plz help me

This is a discussion on hi i am new plz help me within the C Programming forums, part of the General Programming Boards category; i attached the code below The i/p txt file is like this 939,MUM,ord,396,2,3.0,4.0 100,bom,nru,1009,10,4.0,6.0 and i want to add 3.0+4.0=7.0 ...

  1. #1
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    Thumbs down hi i am new plz help me

    i attached the code below
    The i/p txt file is like this
    939,MUM,ord,396,2,3.0,4.0
    100,bom,nru,1009,10,4.0,6.0

    and i want to add 3.0+4.0=7.0
    i.e
    First i want to read the txt file add last two columns writing it into another txt I written the code and i run the code i am getting
    ------------------------------------
    939,MUM,ord,396,2,3.0,4.0
    100,bom,nru,1009,10,4.0,6.0

    Segmentation fault(coredump)
    ----------------------------------------------

    please help me in this

    Thanks & regards
    vijay
    Attached Files Attached Files
    Last edited by vijay85; 01-13-2009 at 10:29 AM. Reason: not properly formatted

  2. #2
    and the hat of wrongness Salem's Avatar
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    1. Learn to indent code, eg.
    Code:
    #include<stdio.h>
    void main()
    {
        char temp[10];
        FILE *input1 = NULL;
        FILE *input2 = NULL;
        unsigned char buffer[100], lTempData[7][20];
        char *lPtr = NULL;
        int i =0;
        input1 = fopen("/u/n073313/vijay/File.txt", "rb");
    
        fread(buffer, 1,100, input1);
        {
            printf("First line %s\n",buffer);
            lPtr = strtok(buffer, ",");
    
            strncpy(lTempData[i], lPtr, strlen(lPtr));
    
            while (lPtr != NULL)
            {
                i++;
                strncpy(lTempData[i], lPtr, strlen(lPtr));
            }
    
            for (int j =0; j< 7 ; j++)
                printf("Values %s\n", lTempData[i]);
    
            int a = atol(lTempData[5]);
            int b = atol(lTempData[6]);
    
            int c = a+b;
    
            printf("Values %d %d result %d\n", a, b, c);
            sprintf(temp, "%d", c);
            input2 = fopen("File2.txt", "r");
            fwrite(c, 1, 10, input2);
            fclose(input1);
            fclose(input2);
    
        }
    
    }
    2. main returns int, not void.

    3. using fread to read a text file is very poor.
    a) it won't stop at a newline
    b) it won't have a \0, for the benefit of the following string functions
    c) it should have been in a loop, if you want to process the whole file.
    Code:
    while ( fgets( buffer, sizeof buffer, input1 ) != NULL ) {
      // do stuff with each line
    }
    4. strncpy(lTempData[i], lPtr, strlen(lPtr));
    It's nice that you're using strncpy to protect your strings from overflow, but
    a) you should use the size of the destination, not the size of the source
    b) you also need to ensure a \0 is copied (strncpy doesn't always do this).

    5. while (lPtr != NULL)
    What changed lPtr in this loop?
    If it gets into the loop, it's not getting out anytime soon.
    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.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  3. #3
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    thanks for reply salem.
    Code:
    :
    #include<stdio.h>
    void main()
    {
    char temp[10];
    FILE *input1 = NULL;
    FILE *input2 = NULL;
    unsigned char buffer[100], lTempData[7][20];
    char *lPtr = NULL;
    int i =0;
    input1 = fopen("/u/n073313/vijay/File.txt", "rb");
    
    fread(buffer, 1,100, input1);
    {
    printf("First line %s\n",buffer);
    lPtr = strtok(buffer, ",");
    
    strncpy(lTempData[i], lPtr, strlen(lPtr));
    
    while ( fgets( buffer, sizeof buffer, input1 ) != NULL )
    {
    i++;
    strncpy(lTempData[i], lPtr, strlen(lPtr));
    }
    
    for (int j =0; j< 7 ; j++)
    printf("Values %s\n", lTempData[i]);
    
    int a = atol(lTempData[5]);
    int b = atol(lTempData[6]);
    
    int c = a+b;
    
    printf("Values %d %d result %d\n", a, b, c);
    sprintf(temp, "%d", c);
    input2 = fopen("File2.txt", "r");
    fwrite(c, 1, 10, input2);
    fclose(input1);
    fclose(input2);
    
    }
    
    }
    i changed as u mentioned but i am getting the o/p as
    ----------------------------------
    cc -o vijay vijay.c
    "vijay.c", line 15.6: 1506-068 (W) Operation between types "char*" and "int" is not allowed.
    "vijay.c", line 36.8: 1506-280 (W) Function argument assignment between types "const void*" and "int" is not allowed.
    $ ./vijay
    First line 939,MUM,ord,396,2,3.0,4.0
    100,bom,nru,1009,10,4.0,6.0

    Values 939
    Values 939
    Values 939
    Values 939
    Values 939
    Values 939
    Values 939
    Values 0 0 result 0
    Segmentation fault(coredump)
    -------------------------------------------------------------
    please help me in this
    thanks & regards
    vijay

  4. #4
    C++まいる!Cをこわせ! Elysia's Avatar
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    1) You did not make the changes Salem requested. You have not indented the code and main still return void, not int as it should be!
    2) If you don't mind, point out on what lines the error occurs!
    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.

  5. #5
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    Line 15:
    Code:
    lPtr = strtok(buffer, ",");
    Perhaps you are missing the prototype for strtok?


    Line 36 is this:
    Code:
    	fwrite(c, 1, 10, input2);
    Since 'c' is an integer, not the address of the data you want to write, I'm not at all surprised. Also, you are trying to write 10 items of 1 byte each - an integer is not 10 bytes in any architecture I know of.

    --
    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.

  6. #6
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    hi i changed from void main() to int main().
    even though i am experiencing the same problem.

  7. #7
    CSharpener vart's Avatar
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    Code:
    fread(buffer, 1,100, input1);
    {
    printf("First line %s\n",buffer);
    lPtr = strtok(buffer, ",");
    Who said that after fread the buffer is nul-terminated?
    and you are using functions that will work correctly only on the nul-terminated strings
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  8. #8
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    Code:
    #include<stdio.h>
    int main()
    {
    char temp[10];
    FILE *input1 = NULL;
    FILE *input2 = input2 = fopen("File2.txt", "w");
    unsigned char buffer[100], lTempData[7][20];
    char *lPtr = NULL;
    int i =0;
    input1 = fopen("/u/n073313/vijay/File.txt", "rb");
    
    fread(buffer, 1,100, input1);
    {
    printf("First line \n%s\n",buffer);
    lPtr = strtok(buffer, ",");
    
    strncpy(lTempData[i], lPtr, strlen(lPtr));
    
    while ( fgets( buffer, sizeof buffer, input1 ) != NULL )
    {
    i++;
    strncpy(lTempData[i], lPtr, strlen(lPtr));
    }
    
    for (int j =0; j< 7 ; j++)
    printf("Values %s\n", lTempData[i]);
    
    int a = atol(lTempData[5]);
    int b = atol(lTempData[6]);
    
    int c = a+b;
    
    printf("Values %d %d result %d\n", a, b, c);
    sprintf(temp, "%d", c);
    input2 = fopen("File2.txt", "r");
    fwrite(c, 1, 10, input2);
    fclose(input1);
    fclose(input2);
    
    }
    
    }
    o/p i am getting is

    $ cc -o vijay vijay.c
    "vijay.c", line 15.6: 1506-068 (W) Operation between types "char*" and "int" is not allowed.
    "vijay.c", line 36.8: 1506-280 (W) Function argument assignment between types "const void*" and "int" is not allowed.
    $ ./vijay
    First line
    939,MUM,ord,396,2,3.0,4.0
    100,bom,nru,1009,10,4.0,6.0

    Values 939
    Values 939
    Values 939
    Values 939
    Values 939
    Values 939
    Values 939
    Values 0 0 result 0

    the code above is not adding 3.0+4.0=7.0 & 4.0+6.0=10.0

    please help in this
    The requirement i have is first opening a .txt file reading the .txt file adding last two colums and writing the output in another .txt file.
    Hope i am clear with my requirement.

  9. #9
    Kernel hacker
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    Ok, so you have change void main to int main, which is correct change, but it's not one of the more important ones - it certainly won't fix the errors/warnings you are seeing. I suggested what those are caused by.

    You are reading using fgets, but:
    Code:
    fread(buffer, 1,100, input1);
    what is this line doing?


    --
    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.

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