C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Re: Nested For Loop Query          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Francis Glassborow Guest Posted: Sun Aug 17, 2003 4:38 pm    Post subject: Re: Nested For Loop Query In article <417ujv4sk9nsnnpaka9r2b0r1tcl5lrs0s (AT) 4ax (DOT) com>, [email]Anonymous (AT) mulgara (DOT) westnet.com.au[/email] writes Quote: #include #include using namespace std; void main(void) check the required signature for main(); it is defined to return an int. Quote: { const int rows(10); const char caret('^'); const int offset(2); for(int row = 0; row < rows; ++row) { cout << setw(rows * offset - row * offset - 1); Instead of messing with manipulators, just out put the required number of spaces. You are vulnerable to a change from pre-standard C++ if you use setw and then output a char. Quote: for(int carets = 1; carets < row * offset + offset; ++carets) cout << caret; cout << 'n'; } } What do you suggest? -- Francis Glassborow ACCU 64 Southfield Rd Oxford OX4 1PA +44(0)1865 246490 All opinions are mine and do not represent those of any organisation [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Dhruv Guest Posted: Sun Aug 17, 2003 4:41 pm    Post subject: Re: Nested For Loop Query On Sun, 17 Aug 2003 07:44:08 -0400, Anonymou wrote: Quote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: [snip]...... Quote: What do you suggest? I would suggest using recursion for such type of problems instead of the nested for loop approach, which means that you have to do all the calculation yourself. Using recursion, you can make the compiler do all the dirty work, and code for only an atomic case. Regards, -Dhruv. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Roger Willcocks Guest Posted: Mon Aug 18, 2003 10:52 am    Post subject: Re: Nested For Loop Query <Anonymous (AT) mulgara (DOT) westnet.com.au> wrote Quote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: .... What do you suggest? I would note that each row contains the same number of characters; the first row is 9 0 [1] 0 9 (spaces carets [caret] carets spaces) the second: 8 1 [1] 1 8 the third: 7 2 [1] 2 7 etc. until everything is carats. -- Roger [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Michiel Salters Guest Posted: Mon Aug 18, 2003 4:40 pm    Post subject: Re: Nested For Loop Query [email]Anonymous (AT) mulgara (DOT) westnet.com.au[/email] wrote in message news:<417ujv4sk9nsnnpaka9r2b0r1tcl5lrs0s (AT) 4ax (DOT) com>... Quote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: ^ ^^^ ^^^^^ ^^^^^^^ ^^^^^^^^^ ^^^^^^^^^^^ What do you suggest? I would use a single loop, and within the loop I'd use the std::string constructor that takes a character count and a fill character to create a string of spaces and another string of carets. HTH, -- Michiel Salters [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Francis Glassborow Guest Posted: Mon Aug 18, 2003 5:18 pm    Post subject: Re: Nested For Loop Query In article <pan.2003.08.17.14.37.45.709236 (AT) gmx (DOT) net>, Dhruv <dhruvbird (AT) gmx (DOT) net> writes Quote: On Sun, 17 Aug 2003 07:44:08 -0400, Anonymou wrote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: [snip]...... What do you suggest? I would suggest using recursion for such type of problems instead of the nested for loop approach, which means that you have to do all the calculation yourself. Using recursion, you can make the compiler do all the dirty work, and code for only an atomic case. I would definitely NOT encourage the use of recursion for such tasks. Good compilers can often convert a tail recursive function to iteration but that is not an excuse for a programmer using recursion. -- Francis Glassborow ACCU 64 Southfield Rd Oxford OX4 1PA +44(0)1865 246490 All opinions are mine and do not represent those of any organisation [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Carl Barron Guest Posted: Mon Aug 18, 2003 5:19 pm    Post subject: Re: Nested For Loop Query Dhruv <dhruvbird (AT) gmx (DOT) net> wrote: Quote: On Sun, 17 Aug 2003 07:44:08 -0400, Anonymou wrote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: [snip]...... What do you suggest? I would suggest using recursion for such type of problems instead of the nested for loop approach, which means that you have to do all the calculation yourself. Using recursion, you can make the compiler do all the dirty work, and code for only an atomic case. Regards, -Dhruv. Recursion? it is easy to do iteratively creating a side in a '3d' look of a pyramid. Simple analysis will determine how many of each character to write on each line so you can get a '3d' pyramid, provided the # of sides meets a simple criterion [ 10 satisfies this as does 13 and 28 and may others.] Just think it through and you can get results with two outer loops and three inner loops in each outer loop, all loops use ++,-- arithmetic. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Carl Barron Guest Posted: Mon Aug 18, 2003 5:19 pm    Post subject: Re: Nested For Loop Query <Anonymous (AT) mulgara (DOT) westnet.com.au> wrote: Quote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: [snip] What do you suggest? is this like what you want? ^ ^^^* ^^^^^** ^^^^^^^*** ^^^^^^^^^**** ^^^^^^^^^^^***** ^^^^^^^^^^^^^****** ^^^^^^^^^^^^^^^**** ^^^^^^^^^^^^^^^^^** ^^^^^^^^^^^^^^^^^^^ [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top John Potter Guest Posted: Tue Aug 19, 2003 12:16 am    Post subject: Re: Nested For Loop Query On 17 Aug 2003 07:44:08 -0400, [email]Anonymous (AT) mulgara (DOT) westnet.com.au[/email] wrote: Quote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} Sorry, I see nothing but a simple math error. Quote: I am trying to display the following pyramid using nested for loops: ^ ^^^ ^^^^^ ^^^^^^^ ^^^^^^^^^ ^^^^^^^^^^^ ^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^ Use a fixed pitch when creating these pictures. The above desired output looks almost identical to your actual output on my screen. It is a triangle with the right symbol of the last line one space left of the others. Quote: So far, I have the following code, but cannot seem to create the pyramid - only a triangle shape occurs: #include #include using namespace std; void main(void) Say int main () when posting to C++ groups to avoid unhelpful replies. Main is required to return int and this code will fail to compile on a very strict compiler. It obviously has nothing to do with your problem. Quote: { const int rows(10); const char caret('^'); const int offset(2); I appreciate the desire for named constants; however, I can't follow the meaning of offset in this case. Sometimes the literal is more meaningful than any name you could give it. It does mean 2 and is used as a multiplier. Quote: for(int row = 0; row < rows; ++row) { cout << setw(rows * offset - row * offset - 1); I know that your assignment requires use of nested for loops and setw. Your code is structured as required. The math error is in the setw. The number of carets is 2r+1, but the number of leading spaces is 10-r. The doubling only applies to the carets. Quote: for(int carets = 1; carets < row * offset + offset; ++carets) cout << caret; cout << 'n'; } } What do you suggest? Look at what is happening. You are getting twice as many spaces as you want. There is a times two in the setw. Remove that and see what happens. Only off by one now. Remove the minus one and get what you want. Much faster than posting to this group. Now go back to the problem and discover what error in thinking produced the original code. The last part is very important. Not because it will prevent you from making it again, but because you will recognize it when it happens. The major difference between experienced programmers and new ones is that the former have made most of the errors already. The first time is painful for everyone. As a general suggestion for homework problems, state up front that it is a homework problem and the requirements such as nested loops using setw in the outer as in this example. That will stop replies from stating that you have a dumb solution, but will not stop them from stating that you have a dumb instructor. Instructional goals often have nothing to do with the professional goals of most people here in this group. Given that you do that and post your attempt which does not work, it is likely to be rejected as trivial here. A better place would be alt.comp.lang.learn.c-c++. You may still get a bunch of responses that are of little or no help, but at least they will get to you quicker as will the good ones. John [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top AngleWyrm Guest Posted: Tue Aug 19, 2003 12:32 am    Post subject: Re: Nested For Loop Query <Anonymous (AT) mulgara (DOT) westnet.com.au> wrote Quote: {This looks like homework but the code includes elements of more general interest. Please address those but be careful not to do his homework:-) -mod} I am trying to display the following pyramid using nested for loops: To debug this code, add a cout statement like so: for(int row = 0; row < rows; ++row) { cout << setw(rows * offset - row * offset - 1); cout << rows * offset - row*offset - 1; // THIS SHOWS THE PROBLEM for(int carets = 1; carets < row * offset + offset; ++carets) cout << caret; The formula you are using for your setw() function is producing values 19,17,15,...,1 for your leading white space. Try rewriting your formula to something that will produce values starting from the middle-1 and going down, instead of the end. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top John Potter Guest Posted: Tue Aug 19, 2003 12:32 am    Post subject: Re: Nested For Loop Query On 18 Aug 2003 13:19:17 -0400, [email]cbarron3 (AT) ix (DOT) netcom.com[/email] (Carl Barron) wrote: Quote: Recursion? it is easy to do iteratively creating a side in a '3d' look of a pyramid. Simple analysis will determine how many of each character to write on each line so you can get a '3d' pyramid, provided the # of sides meets a simple criterion [ 10 satisfies this as does 13 and 28 and may others.] Just think it through and you can get results with two outer loops and three inner loops in each outer loop, all loops use ++,-- arithmetic. What does that have to do with anything? The poor student needs to print a picture of an isosceles triangle using two nested for loops and setw, but his program prints a right triangle. Fixed pitch Desired: ^ ^^^ ^^^^^ ^^^^^^^ Program: ^ ^^^ ^^^^^ ^^^^^^^ Asking simple questions on this group may be impossible useless. John [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. 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