CODEWITHSUNDEEP
c++functionintvoid
soniccool
soniccool

Reputation: 6058

Void vs Int Functions

What would be the different between void and int functions? When do i use which? Would void be used when just printing out a message or a variable value? like cout << value;

Or would it just be text?

And is int used when you actually do calculations within it?

Upvotes: 2

Views: 72280

Answers (8)

Juan Pablo
Juan Pablo

Reputation: 1223

Another difference is that void function do not require to have a return inside it: This 2 snippets of code are valid and do not generate a compiler warning: Snippet 1

void msg1()
{
    cout<< "This is a message." << endl;
    return; // returns nothing or void

}

Snippet 2

void msg2()
{
    cout<< "This is a message." << endl;
}

Both have the same behavior and no warning is displayed.

If you declare a function non void and you do not return a value your compiler is likely to display a WARNING like " warning: no return statement in function returning non-void".

It's depends on modifier parameters sent to compiler if this error is displayed or not.

This code is likey to display a compiler warning since no return :

int test(){
    printf("test");
}

Upvotes: 0

user3220696
user3220696

Reputation:

Actually,It is necessary if you are compiling your code for a hosted system, such as PC, Linux, Mac, Android. Then main must return int. If you are compiling code for a freestanding system, such as embedded microcontrollers, or if you are making an OS, then the return type of main can be anything.

Though no error will occur if you use int or void but its not compliance according to standard C.

Upvotes: -2

Kusavil
Kusavil

Reputation: 295

Like you heard above, void doesn't return value, so you use it when you don't need to do this. For example, you can use 'void' not only to print text, but mainly to modificate a parameters (change something you already have), so you don't need to return a value.

Let's say you want to find int c , which is sum two (integer) numbers, a and b (so a+b=c). You can write a function which adds these numbers and assign it's value to c

int c;
int sum (int a, int b)
{
    return a+b;     
}       

c = sum(a,b);

While using void, you will just modificate c, so instead of writing c = function(arguments) , you will have function(c) which modifies c, for example:

int c;
void sum(int a, int b, int c)
    {
        c = a+b;
    }

sum(a,b,c);

After the last line, the 'c' you have is equal the sum of 'a' and 'b' :-)

Upvotes: 1

Fitz Chen
Fitz Chen

Reputation: 11

when you use void, it means you don't want anything returned from the function. while an int return may be a result of calculation in the function, or indicate the status when it returning, such as an error number or something else that can tell you what has happened when the function executing.

Upvotes: 1

Ahmed Khalaf
Ahmed Khalaf

Reputation: 1419

Some prefer using functions that return int to indicate some errors or special cases. Consider this code:

int print (int* ptr)
{
    if (ptr == NULL)
    {
        return -1; // Error code.
    }

    std::cout << *ptr;

    return 1; // Success code.
}

Upvotes: 1

srikanta
srikanta

Reputation: 2999

void is used when you are not required to return anything from the function to the caller of the function.

for eg.

void no_return_fn()
{
    cout<< "This function will not return anything" << endl;
    return; // returns nothing or void

}

int is used when you have to return an integer value from the function to the caller of the function

for eg.

int return_sum_of_integers_fn(int a, int b)
{
    cout<< "This function returns an integer" << endl;
    return (a + b); // returns an integer
}

Upvotes: 8

duffymo
duffymo

Reputation: 308938

You return void to indicate that nothing is returned.

An int return may or may not indicate that calculations have been performed (e.g. could just be a return code).

Upvotes: 0

Beta
Beta

Reputation: 99134

Do you want the function to return anything? If not, then it should be void. If you want it to return an int, then it should be int. If you want it to return something else, then it should have some other return type.

Upvotes: 4

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