program explanation

This is a discussion on program explanation within the C Programming forums, part of the General Programming Boards category; Code: #include <stdio.h> void main() { int a,b; for(a=0;a<6;++a){ for(b=0;b<=a;++b) putchar('*'); putchar('\n'); } } This generates the figure: * ** ...

  1. #1
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    program explanation

    Code:
    #include <stdio.h>
    
    void main()
    {
    	int a,b;
    
    	for(a=0;a<6;++a){
    		for(b=0;b<=a;++b)
    			putchar('*');
    			putchar('\n');
    	}
    }
    This generates the figure:
    *
    **
    ***
    ****
    *****
    ******
    Could someone dissect each for statement and the entire loop as well?
    What I don't get is how it knows to print just 1 * first, then 2 ...
    Sorry for being such a newbie ... and thanks.

  2. #2
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    hmm, read a book on the for statement, then take about 5 minutes to look at the tiny piece of code and you will figure it out and have a better understanding of for loops!

  3. #3
    cwr
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    Your indentation is lying, the indentation that reflects what is actually happening is like this:
    Code:
    #include <stdio.h>
    
    int main(void) /* main returns int, not void */
    {
        int a,b;
        for (a = 0; a < 6; ++a)
        {
            for (b = 0; b <= a; ++b)
                putchar('*'); /*only one statement in the inner for, because there are no braces */
            putchar('\n');
        }
        return 0;
    }
    Make more sense now?

  4. #4
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    CWR - thanks ... and not really, but i copied it down and i'll analyze it.

    rockytriton - what book would you suggest? for beginners and with lots of sample programs and exercises i can study?

  5. #5
    Bond sunnypalsingh's Avatar
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    Quote Originally Posted by markg
    rockytriton - what book would you suggest? for beginners and with lots of sample programs and exercises i can study?
    You can study tutorials on this site itself.....good collection of tutorials are available on this site

  6. #6
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    any book that contains the phrases "c++" and "beginner", or like sunny suggest, use a tutorial, but not all tutorials will actually explain how things work well.

  7. #7
    cwr
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    Work through the code in your head, going through each line and seeing what happens to a and b. If that is too difficult, add some diagnostic printf's to show the values of a and b, or run it through a debugger.

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