Tokenizing the string problem

This is a discussion on Tokenizing the string problem within the C Programming forums, part of the General Programming Boards category; What I need to do is set num = 2 as it specified in server.conf. At num=atoi(strtok(NULL,"=")); I am getting ...

  1. #1
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    Tokenizing the string problem

    What I need to do is set num = 2 as it specified in server.conf. At num=atoi(strtok(NULL,"=")); I am getting segfault there or it is giving out 0. I am running linux and gcc 4.1.2.

    server.conf:
    Code:
    num_of_files=2;
    myprog.c:
    Code:
    int c, num;
    char buf[100],buf1[100];
    	
    c=open("./server.conf",O_RDONLY);
    read(c,buf,sizeof buf);
    close(c);
    	
    buf1=strtok(buf,";");
    strtok(buf1,"=");
    num=atoi(strtok(NULL,"="));  //I am getting segfault here or it is giving out 0.
    Last edited by 911help; 12-27-2007 at 05:58 AM.

  2. #2
    ZuK
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    read dosn't 0-terminate the string that you read.
    BTW this shouldn't compile. You're trying to assign a pointer to an arry
    Code:
    buf1=strtok(buf,";");
    Kurt

  3. #3
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    Sorry my bad it should of been:
    Code:
    char buf[100];
    char *buf1;
    I am not sure why I get segfault or 0 here.
    num=atoi(strtok(NULL,"=")); //I am getting segfault here or it is giving out 0.

    Can someone help. I spent whole day trying figure this out.

  4. #4
    Deathray Engineer MacGyver's Avatar
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    Quote Originally Posted by 911help View Post
    I am not sure why I get segfault or 0 here.
    Read this again:

    Quote Originally Posted by ZuK View Post
    read dosn't 0-terminate the string that you read.

  5. #5
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    Rather than:
    Code:
    c=open("./server.conf",O_RDONLY);
    read(c,buf,sizeof buf);
    close(c);
    Change it to this:
    Code:
    c=open("./server.conf",O_RDONLY);
    read(c,buf,99);
    close(c);
    buf[99] ="\0";
    Would this fix it?

  6. #6
    Registered User ssharish2005's Avatar
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    Why don't you open your while using fopen with the normal text mode and use fgets to read a line from there. Rather than

    Code:
    c=open("./server.conf",O_RDONLY);
    Perhaps doing that way your buf will be terminated by '\0' by fgets itself, reducing your overhead on you explicitly inserting a '\'0 char.

    ssharish

  7. #7
    C++まいる!Cをこわせ! Elysia's Avatar
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    Quote Originally Posted by 911help View Post
    Code:
    buf[99] ="\0";
    Must be:
    Code:
    buf[99] = '\0';
    Else it won't compile. You must learn to differentiate between a string and character. "" = string, '' = character.
    A string is an array of character, so when you assign to an index in the array, you must assign a character, and not a string.
    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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