Programming Forums > Application Development > C++

mfo6463 · Feb 8th, 2006, 4:13 PM

Is there a way to make a struct from a variable's content?

So if I have this:

char name[20];
cin >> name;
cout << name;

struct test
{
     int test;
};

test ???;

Those three question marks... I want to replace that with the value of "name" but I don't know how.

example:
If the user typed in "John" for "name" then this would happen:

(Toggle Plain Text)

test John;

I hope that makes sense...

Wizard1988 · Feb 8th, 2006, 4:16 PM

in your code test is an integer and name is a character array. Therefore I don't think you can do that.

mfo6463 · Feb 8th, 2006, 4:25 PM

Quote:

Originally Posted by Wizard1988

in your code test is an integer and name is a character array. Therefore I don't think you can do that.

I'm not talking about the integer in the struct, I'm talking about the struct itself.

Seif · Feb 8th, 2006, 4:45 PM

you would need the char name[20] in the struct man like so:

(Toggle Plain Text)

struct test
{
     int test;
     char name[20]
};

test newTest;

unless im reading you wrong :/

Seif · Feb 8th, 2006, 4:47 PM

oh and to change the name is like

(Toggle Plain Text)

cin >> newTest.test
cin.getline(newTest.name,20);

mfo6463 · Feb 8th, 2006, 5:00 PM

I think you're reading me wrong.

Ok I'll use your code as the example to try to explain a little better.

You put "test newTest;" to create a test struct called "newTest"

I want "newTest" to be whatever the user types in, so the user is actually selecting the name of the struct instead of it being "newTest"

So the user would be pretty much creating the struct.

DaWei · Feb 8th, 2006, 5:07 PM

No.....

Seif · Feb 8th, 2006, 5:13 PM

ah right i see. dont think you can do that. if you want it so you can find the struct, keep the name field in the new struct and create a linked list, where you can find it by performing a strcmp on a user input.

DaWei · Feb 8th, 2006, 5:34 PM

Think about it like this: input comes at runtime. What are you running? Something that doesn't exist until you run it? There are some things that can be manipulated at runtime. The groundwork has to be laid in advance.

A wise gardener once said, "It is better to leave a person flowerless than to sling shit at a person asking for roses."

mfo6463 · Feb 8th, 2006, 5:44 PM

Ok, I'll try the linked list suggestion.

Thanks for the help.

Feb 8th, 2006, 4:13 PM	#1
mfo6463 Newbie Join Date: Nov 2004 Posts: 10 Rep Power: 0	create struct from value of a variable Is there a way to make a struct from a variable's content? So if I have this: (Toggle Plain Text) char name[20]; cin >> name; cout << name; struct test { int test; }; test ???; char name[20]; cin >> name; cout << name; struct test { int test; }; test ???; Those three question marks... I want to replace that with the value of "name" but I don't know how. example: If the user typed in "John" for "name" then this would happen: (Toggle Plain Text) test John; test John; I hope that makes sense...

Feb 8th, 2006, 4:45 PM	#4
Seif Hobbyist Programmer Join Date: Jan 2006 Location: UK Posts: 215 Rep Power: 3	you would need the char name[20] in the struct man like so: (Toggle Plain Text) struct test { int test; char name[20] }; test newTest; struct test { int test; char name[20] }; test newTest; unless im reading you wrong :/

Feb 8th, 2006, 4:47 PM	#5
Seif Hobbyist Programmer Join Date: Jan 2006 Location: UK Posts: 215 Rep Power: 3	oh and to change the name is like (Toggle Plain Text) cin >> newTest.test cin.getline(newTest.name,20); cin >> newTest.test cin.getline(newTest.name,20);

Feb 8th, 2006, 5:07 PM	#7
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	No..... __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Feb 8th, 2006, 5:34 PM	#9
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Think about it like this: input comes at runtime. What are you running? Something that doesn't exist until you run it? There are some things that can be manipulated at runtime. The groundwork has to be laid in advance. A wise gardener once said, "It is better to leave a person flowerless than to sling shit at a person asking for roses." __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Feb 8th, 2006, 4:16 PM	#2
Wizard1988 Professional Programmer Join Date: Oct 2005 Location: Chitown Posts: 417 Rep Power: 4	in your code test is an integer and name is a character array. Therefore I don't think you can do that.

Feb 8th, 2006, 5:00 PM	#6
mfo6463 Newbie Join Date: Nov 2004 Posts: 10 Rep Power: 0	I think you're reading me wrong. Ok I'll use your code as the example to try to explain a little better. You put "test newTest;" to create a test struct called "newTest" I want "newTest" to be whatever the user types in, so the user is actually selecting the name of the struct instead of it being "newTest" So the user would be pretty much creating the struct.

Feb 8th, 2006, 5:13 PM	#8
Seif Hobbyist Programmer Join Date: Jan 2006 Location: UK Posts: 215 Rep Power: 3	ah right i see. dont think you can do that. if you want it so you can find the struct, keep the name field in the new struct and create a linked list, where you can find it by performing a strcmp on a user input.

Feb 8th, 2006, 5:44 PM	#10
mfo6463 Newbie Join Date: Nov 2004 Posts: 10 Rep Power: 0	Ok, I'll try the linked list suggestion. Thanks for the help.

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Programming Forums > Application Development > C++

create struct from value of a variable