Need example of declaration.

[fikri]

hi guys,i need help with c++ declaration example.

such as intenger,character,floating and string. i really appreciate it if someone will help me out.

thanx.

[R0mai]

http://www.cplusplus.com/doc/tutorial/
http://www.cplusplus.com/doc/tutorial/variables/

[fikri]

argh,i still couldnt understand some of it..do u have any idea where i could find more? bcause i already googled, and lots of them not for newcomer like me.

[R0mai]

Ok, then, maybe you should post some code which you don't understand, and then we can help make it clear for you :)

[kbw]

There are books on the matter, like the C++ Primer by Limpann and Lajoie but what is it you don't understand?

[fikri]

hmm,i think i just make you guys confused.sorry. i need to know example of declaration each for data types. whether integer,char,float or string.

[jsmith]

I think the understanding is that you want to know how to declare a variable of a certain type (such as integer, etc).

The responses are basically that declaring variables is the most fundamental aspect of computer programming,
and in virtually any given piece of C++ code you can find on the 'net, you will see examples of variable declarations.
Just look at any post here that has code in it if the tutorials are too advanced (though it does not get any simpler than the "Declaration of variables" section in http://www.cplusplus.com/doc/tutorial/variables/ ).

[chrisname]

int myInt;
float myFloat;
char myChar;
std::string myStr;
long myLongInt;
double myDoublePrecisionFloat;
int myIntArray[amountOfElements];
char myCharArray[amountOfElements];
std::string YepEvenThisWorks[amountOfElements];

What don't you understand?

[Alan]

'int' type

int x = 5;

the (simplest) format for declaring variables is

type variable_name;

or type variable_name = value;

you can also declare variable of the same type in one line:
type variable1, variable2, variable3; // ... or type variable1=value, variable2=value; // ...

here is an example of many types of variable declarations

int i1;
int i2 = 5;
int i3 = 5i;
int i4, i5, i6;
int i4 = 1, i5 = 2, i6 = 3;

char c1;
char c2 = 'a';
char c3 = 97; // 97 = 'a' on ascii chart
char i4, i5, i6;
char i4 = 'A', i5 = 'B', i6 = 'C';

float f1;
float f2 = 5.5;
float f3 = 5.5f;
float i4, i5, i6;
float i4 = 1.1, i5 = 2.2, i6 = 3.3;

std::string s1;
std::string s2 = "Hello";
std::string s3("Hello"); // since string is a class...
std::string i4, i5, i6;
std::string i4 = "Hi", i5 = "Hey", i6 = "Hola";

now that we have some code posted ask about anything that confuses you...

[fikri]

thanx a lot guys. ill think i get it. but Alan,what about float? i mean for double.how to declare it?

[Alan]

the same as any other... the double/float type is just used to store a number that has a decimal value.

double d1; // makes a double variable with no value
double d2 = 1.5; // makes a double variable with the value 1.5
double d3 = 2; // makes a double variable with the value 2 

[fikri]

-edited-

[fikri]

oh i think i get it now.....thanx a lot for saving my day! i owe you guys. :D

[chrisname]

Always remember to assign a value to the variable before you use it. For an example of why, try the following code:
char charArray[80];
for (int i = 0; i < 80; ++i)
std::cout << charArray[i];

You should see a bunch of characters. Maybe even different ones everytime you run the code.

As good practice, assign 0 to numerical types such as ints and floats, '\0' to chars, and "\0" to strings, e.g.
int myInt = 0;
char myChar = '\0';
std::string myStr = "\0";

[fikri]

thanx for the tip chris. for your information, i havent start compiling any programs yet,im a newcomer to c++ world. haha.

[mcleano]

i havent start compiling any programs yet,im a newcomer to c++

Make sure you have a balance of "book" work and practical work. By that I mean don't just read information/tutorials, actually give them ago and create things using given ideas and some of your own.

[R0mai]

chrisname : "\0" is a waste of space since "" //empty string is a null-terminated 0 lenght string (e.g: an 1 lenght array consiting a 0), while "\0" is a 2 lenght array consisting two 0s.

[Duthomhas]

To have embedded null characters in the string you need to specify the length of the string (which does not include the terminating null):
std::string s( "\0", 1 );

[helios]

Well... That's true, but it doesn't make much of a difference, for the most part. All instances of "\0" probably point to the same string, so the binary is only one char longer. std::string::string(const char *) will only read until the first zero, so it'll just create a zero length string. These are almost equivalent:
std::string s;
std::string s="";
The latter may run a few more instructions, since it needs to check the size of the C string.

EDIT: I'm replying to R0mai.

[R0mai]

helios : Other than the 1 byte memory overhead that "" has, in my eye it's much more readable than "\0", because "" is actually empty, but in "\0" there is one extra character which makes it look like it's not empty.

Anyway I've never seen "\0" before, that's why my eye caught up on this :)

Good night!