Urgent Variable Question

[benzedrine]

hello. here is my problem-


say i have variables:

* int a, b, c, d;
string x; *

the string x contains one of four options- a, b, c, d.

now i need a way without using:

* if(x=="a") {..}
if(x=="b") {..}
if(x=="c") {..}
if(x=="d") {..} *

to store a number in one of those variables (a\b\c\d) that are what contained in string x..

for example-
string x="c";
so then i use some kind of *cin>>* function to store some number inside the variable c..

can anyone help me??

[Krishnaa]

You mean you dont want to use if else conditions ?

Any reason ?

[AsaF]

hello. here is my problem-

to store a number in one of those variables (a\b\c\d) that are what contained in string x..

for example-
string x="c";
so then i use some kind of *cin>>* function to store some number inside the variable c..

I really don't get what you want to do? It probably easy programming when you can explain exactly what you want... :-D

[Viorel]

Maybe you need something like this:

int a, b, c, d;
string x = "c";
int * p[4] = { &a, &b, &c, &d };

cin >> *p[ x[0] - 'a' ]; // read c

I hope it helps.

[benzedrine]

lol yes im a new programers.. and i maybe really didn't explain my thought to the end..

I'm trying to build a sudoku solver, but forget about the logic and all.. i just use 81 variables (not arrays, but a1, a2 ... i8, i9), and in the start of the program i request the user to input a few starting known cube..

say he chooses a1 (he can choose what ever he likes..) , i store it using:

 string x; cin>>x;

so "a1" is now stored in string x.

i want now to request a number to be placed in the variable ** int a1 **, and that without using:

if(x=="a1") { cin>>a1; }
if(x=="a2") { cin>>a2; }
.
.
if(x=="i8") { cin>>i8; }
if(x=="i9") { cin>>i9; }

[Krishnaa]

You can have the 2 dimensional array of int 9*9, and you can modify the logic to move around X,Y dimensions.

If you are new programmer then I would recommand keeping the program logic As Simple As possible, adding complex algoritms/ways could lose the readability also it can create confusion while debugging.

[Krishnaa]

BTW from where do you get the variable name in string ? like "C" ,"B"...

[benzedrine]

the user inputs them (in a sudoku there are some cubes that their value is known from the start- the program asks the user which cubes are known (cin>>x;) and what is their value (the value of the variable the is stored as a string is x).

[benzedrine]

Maybe you need something like this:

int a, b, c, d;
string x = "c";
int * p[4] = { &a, &b, &c, &d };

cin >> *p[ x[0] - 'a' ]; // read c

I hope it helps.

i tryed this and it doesn't work.
what was it supose to do?

[exterminator]

I think what you need is a way to convert a string type to a numeric type. See the FAQs for the various way of doing so.

Otherwise, what you can do is have a map with string or char as key (this is what the user enters) and the value of the variables correspondingly into map's value part. You would not need any conversions or if-else's this way.

[benzedrine]

i cant find that in the FAQ, anyway im not sure that is what i need (english is not my main language) - string to numeric is not like if string x contains the value "11", so i can convert it to int y = x = 11 ?

[exterminator]

i cant find that in the FAQ, anyway im not sure that is what i need (english is not my main language) - string to numeric is not like if string x contains the value "11", so i can convert it to int y = x = 11 ?

Forget about the conversions, use the map. Here is where you can find how to use it - http://www.cppreference.com/cppmap/index.html

Non-fool-proof sample code:

#include<map>
#include<iostream>
int main()
{
	char user_input;
	std::map<char, int> my_map;
	int a = 10;
	int b = 20;
	my_map['a'] = a;
	my_map['b'] = b;
	
	std::cout << "Enter character\n";
	std::cin >> user_input;
	std::cout << "Corresponding value is : " << my_map[user_input] << "\n";
}

[benzedrine]

Forget about the conversions, use the map. Here is where you can find how to use it - http://www.cppreference.com/cppmap/index.html

Non-fool-proof sample code:

#include<map>
#include<iostream>
int main()
{
	char user_input;
	std::map<char, int> my_map;
	int a = 10;
	int b = 20;
	my_map['a'] = a;
	my_map['b'] = b;
	
	std::cout << "Enter character\n";
	std::cin >> user_input;
	std::cout << "Corresponding value is : " << my_map[user_input] << "\n";
}

actually, tanks, but this doesn't help.. the problem that i had with the most simple way of doing that (using the if statment) is that my code had to contain 81 lines (one for each variable) every time i wanted to do this..
the solution u gave me is just like that..

my_map['a'] = a1;
my_map['b'] = a2;
.
.
.
my_map['a'] = i8;
my_map['b'] = i9;

im looking for a FAST 1-2 lines to solve this and get to the desirable effect, if there is any..
can u think of another solution PLZ?

[benzedrine]

#include <iostream>
#include <string>
#include <map>
using namespace std;
int main()
{
  int a1=0, b1=0, c1=0, d1=0, e1=0, f1=0, g1=0, h1=0, i1=0,
      a2=0, b2=0, c2=0, d2=0, e2=0, f2=0, g2=0, h2=0, i2=0,
      a3=0, b3=0, c3=0, d3=0, e3=0, f3=0, g3=0, h3=0, i3=0,
      a4=0, b4=0, c4=0, d4=0, e4=0, f4=0, g4=0, h4=0, i4=0,
      a5=0, b5=0, c5=0, d5=0, e5=0, f5=0, g5=0, h5=0, i5=0,
      a6=0, b6=0, c6=0, d6=0, e6=0, f6=0, g6=0, h6=0, i6=0,
      a7=0, b7=0, c7=0, d7=0, e7=0, f7=0, g7=0, h7=0, i7=0,
      a8=0, b8=0, c8=0, d8=0, e8=0, f8=0, g8=0, h8=0, i8=0,
      a9=0, b9=0, c9=0, d9=0, e9=0, f9=0, g9=0, h9=0, i9=0;
  int *p[81]={&a1, &a2, &a3, &a4, &a5, &a6, &a7, &a8, &a9, &b1, &b2, &b3, &b4, &b5, &b6, &b7, &b8, &b9,
              &c1, &c2, &c3, &c4, &c5, &c6, &c7, &c8, &c9, &d1, &d2, &d3, &d4, &d5, &d6, &d7, &d8, &d9,
              &e1, &e2, &e3, &e4, &e5, &e6, &e7, &e8, &e9, &f1, &f2, &f3, &f4, &f5, &f6, &f7, &f8, &f9,
              &g1, &g2, &g3, &g4, &g5, &g6, &g7, &g8, &g9, &h1, &h2, &h3, &h4, &h5, &h6, &h7, &h8, &h9,
              &i1, &i2, &i3, &i4, &i5, &i6, &i7, &i8, &i9 };
  string x1="\0";
  
  cout<<"x1 = ";
  cin>>x1;
  
  cout<<endl<<x1<<" = ";
  
  cin>>*p[x1[0]+x1[1]];
  
  cout<<"\na1= "<<a1<<endl
      <<"a2= "<<a2<<endl
      <<"a3= "<<a3<<endl
      <<"a4= "<<a4<<endl
      <<"a5= "<<a5<<endl
      <<"a6= "<<a6<<endl
      <<"a7= "<<a7<<endl
      <<"a8= "<<a8<<endl
      <<"a9= "<<a9<<endl
      <<"b2= "<<b2<<endl      
      <<"f5= "<<f5<<"\n\n";

  return 0;  
}

why doesn't this work? and how can i get it to work?..
thnks

[exterminator]

Can you explain the physical significance of what you are trying to achieve? What do those huge number of variables used for and mean? And how are they to be used? May be then someone could suggest something better.

If all those variables are supposed to be constants, then a file can be used to keep them and hence work with them... but first the answers to above questions are important!