new to C...need to eliminate whitespace

This is a discussion on new to C...need to eliminate whitespace within the C Programming forums, part of the General Programming Boards category; hello i am new to the programming world and was wondering if anyone could help me out with a problem ...

  1. #1
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    Question new to C...need to eliminate whitespace

    hello i am new to the programming world and was wondering if anyone could help me out with a problem i am having.....i need to accept keyboard input, and reproduce it after eliminating whitespace unless in "string literal"....so far i am able to print the input but im not quite sure how im supposed to delete the whitespace....here is what i have so far...

    Code:
    #include <stdio.h>
    
    int main()
    {
       int c;
       
       printf("This program eliminates whitespace from an input stream,\n");
       printf("except from within string literals in double quotes.\n");
       printf("\n");
       printf("Type characters, and enter EOF after <enter> to finish:\n");
       
       while ((c = getchar()) != EOF) {
          putchar(c);
    }
       system("pause");
       
       return 0;
    }
    i dont expect anyone to do this for me....but i have a textbook and notes and i just dont understand how to get this done....if anyone could give me any hints i would appreciate it. thanks

  2. #2
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    Add one bool variable, in_string_literal. Initialize it to false, and toggle it whenever you see a ".

    In the loop, if c is whitespace and in_string_literal is false, don't print it.

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    im sorry but i dont understand what you are saying...i have only taken 3 classes so far in INTRO to C programming....whats is a bool? and how do i toggle? and how do i say string literal is false? im sorry im probably asking really stupid questions but i just dont understand

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    anyone??

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    Wow you are given this assignment after 3 classes? What is your teacher smoking .

    That aside,

    Code:
    bool in_string_literal = false;
    a bool (http://en.wikipedia.org/wiki/Boolean_datatype) is a type (like char or int) that can only have 2 states, true and false.

    Toggle means set it to true if it's false, and set it to false if it's true.
    The easiest way to do that is with an exclusive-or
    Code:
    in_string_literal ^= 1;
    But I am guessing you haven't learned that, yet.
    http://www.cprogramming.com/tutorial...operators.html
    (it's probably a little too advanced for you at this stage, don't worry about it)

    Just use an if, then
    Code:
    if (in_string_literal) {
         in_string_literal = false;
    } else {
         in_string_literal = true;
    }
    how do i say string literal is false?
    Code:
    if (in_string_literal == false)
    or
    Code:
    if (!in_string_literal)

  6. #6
    "I Win!" by U. Lose vart's Avatar
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    this is pure C
    why is it on the C++ board?
    To be or not to be == true

  7. #7
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by vart
    this is pure C
    why is it on the C++ board?
    Indeed, so I have moved it to the C programming forum.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    Just curious if you also need to figure out how to separate a string literal from a line with an embedded double-quote as in.
    => this is a line with an " embedded double-quote
    => "this is a string literal"

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