passing by reference

i have the following program and this is the error i am getting
illegal, right operand has type 'double *
how do i fix it

Code:

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#include<stdlib.h>
#include<stdio.h>
void cube(double* pVariable);
main(){
       
        double variable=3.43;
        int* pVariable;

        printf("Value of variable is &#37;.2lf\n",variable);
        printf("Address of variable is %p\n",&variable);
       
        pVariable=&variable;
        cube(&variable);
       
        system("Pause");
}

void cube(double *pVariable){
        printf("The number %.2lf\n",pVariable);
        pVariable=*pVariable*pVariable*pVariable;
}

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Code:

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>        printf("The number %.2lf\n",pVariable);
>        pVariable=*pVariable*pVariable*pVariable;

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I would imagine you want what the pointer points to, not the pointer itself:

Code:

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        printf("The number %.2lf\n", *pVariable);
        *pVariable = *pVariable * *pVariable * *pVariable;

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Code:

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main()

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Should be

Code:

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int main(void)

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> printf("The number %.2lf\n", *pVariable);
Also unless your compiler supports C99, the correct format specifier for double is %f.

Code:

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        printf("The number %.2f\n", *pVariable);

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Code:

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double variable=3.43;
int* pVariable;
pVariable=&variable;

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Your compiler should be complaining about that assignment: A pointer to double can't be converted to a pointer to int without a cast. That doesn't mean use a cast, though. It means that pVariable should be a pointer to a double.

Does C99 support %lf for printf()? I couldn't find any evidence of this.

It looks like it does support %Lf for long doubles, however. http://linux.die.net/man/3/printf

n869&n1124:7.19.6.1p7

Quote:

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l (ell) Specifies that a following d, i, o, u, x, or X conversion specifier applies to a long int or unsigned long int argument; that a following n conversion specifier applies to a pointer to a long int argument; that a following c conversion specifier applies to a wint_t argument; that a following s conversion specifier applies to a pointer to a wchar_t argument; or has no effect on a following a, A, e, E, f, F, g, or G conversion specifier.

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